
"dis" --- Disassembler for Python bytecode
******************************************

**Source code:** Lib/dis.py

======================================================================

The "dis" module supports the analysis of CPython *bytecode* by
disassembling it. The CPython bytecode which this module takes as an
input is defined in the file "Include/opcode.h" and used by the
compiler and the interpreter.

**CPython implementation detail:** Bytecode is an implementation
detail of the CPython interpreter.  No guarantees are made that
bytecode will not be added, removed, or changed between versions of
Python.  Use of this module should not be considered to work across
Python VMs or Python releases.

Example: Given the function "myfunc()":

   def myfunc(alist):
       return len(alist)

the following command can be used to display the disassembly of
"myfunc()":

   >>> dis.dis(myfunc)
     2           0 LOAD_GLOBAL              0 (len)
                 2 LOAD_FAST                0 (alist)
                 4 CALL_FUNCTION            1
                 6 RETURN_VALUE

(The "2" is a line number).


Bytecode analysis
=================

New in version 3.4.

The bytecode analysis API allows pieces of Python code to be wrapped
in a "Bytecode" object that provides easy access to details of the
compiled code.

class dis.Bytecode(x, *, first_line=None, current_offset=None)

   Analyse the bytecode corresponding to a function, generator,
   method, string of source code, or a code object (as returned by
   "compile()").

   This is a convenience wrapper around many of the functions listed
   below, most notably "get_instructions()", as iterating over a
   "Bytecode" instance yields the bytecode operations as "Instruction"
   instances.

   If *first_line* is not "None", it indicates the line number that
   should be reported for the first source line in the disassembled
   code.  Otherwise, the source line information (if any) is taken
   directly from the disassembled code object.

   If *current_offset* is not "None", it refers to an instruction
   offset in the disassembled code. Setting this means "dis()" will
   display a "current instruction" marker against the specified
   opcode.

   classmethod from_traceback(tb)

      Construct a "Bytecode" instance from the given traceback,
      setting *current_offset* to the instruction responsible for the
      exception.

   codeobj

      The compiled code object.

   first_line

      The first source line of the code object (if available)

   dis()

      Return a formatted view of the bytecode operations (the same as
      printed by "dis.dis()", but returned as a multi-line string).

   info()

      Return a formatted multi-line string with detailed information
      about the code object, like "code_info()".

Example:

   >>> bytecode = dis.Bytecode(myfunc)
   >>> for instr in bytecode:
   ...     print(instr.opname)
   ...
   LOAD_GLOBAL
   LOAD_FAST
   CALL_FUNCTION
   RETURN_VALUE


Analysis functions
==================

The "dis" module also defines the following analysis functions that
convert the input directly to the desired output. They can be useful
if only a single operation is being performed, so the intermediate
analysis object isn't useful:

dis.code_info(x)

   Return a formatted multi-line string with detailed code object
   information for the supplied function, generator, method, source
   code string or code object.

   Note that the exact contents of code info strings are highly
   implementation dependent and they may change arbitrarily across
   Python VMs or Python releases.

   New in version 3.2.

dis.show_code(x, *, file=None)

   Print detailed code object information for the supplied function,
   method, source code string or code object to *file* (or
   "sys.stdout" if *file* is not specified).

   This is a convenient shorthand for "print(code_info(x),
   file=file)", intended for interactive exploration at the
   interpreter prompt.

   New in version 3.2.

   Changed in version 3.4: Added *file* parameter.

dis.dis(x=None, *, file=None)

   Disassemble the *x* object.  *x* can denote either a module, a
   class, a method, a function, a generator, a code object, a string
   of source code or a byte sequence of raw bytecode.  For a module,
   it disassembles all functions. For a class, it disassembles all
   methods (including class and static methods). For a code object or
   sequence of raw bytecode, it prints one line per bytecode
   instruction.  Strings are first compiled to code objects with the
   "compile()" built-in function before being disassembled.  If no
   object is provided, this function disassembles the last traceback.

   The disassembly is written as text to the supplied *file* argument
   if provided and to "sys.stdout" otherwise.

   Changed in version 3.4: Added *file* parameter.

dis.distb(tb=None, *, file=None)

   Disassemble the top-of-stack function of a traceback, using the
   last traceback if none was passed.  The instruction causing the
   exception is indicated.

   The disassembly is written as text to the supplied *file* argument
   if provided and to "sys.stdout" otherwise.

   Changed in version 3.4: Added *file* parameter.

dis.disassemble(code, lasti=-1, *, file=None)
dis.disco(code, lasti=-1, *, file=None)

   Disassemble a code object, indicating the last instruction if
   *lasti* was provided.  The output is divided in the following
   columns:

   1. the line number, for the first instruction of each line

   2. the current instruction, indicated as "-->",

   3. a labelled instruction, indicated with ">>",

   4. the address of the instruction,

   5. the operation code name,

   6. operation parameters, and

   7. interpretation of the parameters in parentheses.

   The parameter interpretation recognizes local and global variable
   names, constant values, branch targets, and compare operators.

   The disassembly is written as text to the supplied *file* argument
   if provided and to "sys.stdout" otherwise.

   Changed in version 3.4: Added *file* parameter.

dis.get_instructions(x, *, first_line=None)

   Return an iterator over the instructions in the supplied function,
   method, source code string or code object.

   The iterator generates a series of "Instruction" named tuples
   giving the details of each operation in the supplied code.

   If *first_line* is not "None", it indicates the line number that
   should be reported for the first source line in the disassembled
   code.  Otherwise, the source line information (if any) is taken
   directly from the disassembled code object.

   New in version 3.4.

dis.findlinestarts(code)

   This generator function uses the "co_firstlineno" and "co_lnotab"
   attributes of the code object *code* to find the offsets which are
   starts of lines in the source code.  They are generated as
   "(offset, lineno)" pairs.

dis.findlabels(code)

   Detect all offsets in the code object *code* which are jump
   targets, and return a list of these offsets.

dis.stack_effect(opcode[, oparg])

   Compute the stack effect of *opcode* with argument *oparg*.

   New in version 3.4.


Python Bytecode Instructions
============================

The "get_instructions()" function and "Bytecode" class provide details
of bytecode instructions as "Instruction" instances:

class dis.Instruction

   Details for a bytecode operation

   opcode

      numeric code for operation, corresponding to the opcode values
      listed below and the bytecode values in the Opcode collections.

   opname

      human readable name for operation

   arg

      numeric argument to operation (if any), otherwise "None"

   argval

      resolved arg value (if known), otherwise same as arg

   argrepr

      human readable description of operation argument

   offset

      start index of operation within bytecode sequence

   starts_line

      line started by this opcode (if any), otherwise "None"

   is_jump_target

      "True" if other code jumps to here, otherwise "False"

   New in version 3.4.

The Python compiler currently generates the following bytecode
instructions.

**General instructions**

NOP

   Do nothing code.  Used as a placeholder by the bytecode optimizer.

POP_TOP

   Removes the top-of-stack (TOS) item.

ROT_TWO

   Swaps the two top-most stack items.

ROT_THREE

   Lifts second and third stack item one position up, moves top down
   to position three.

DUP_TOP

   Duplicates the reference on top of the stack.

DUP_TOP_TWO

   Duplicates the two references on top of the stack, leaving them in
   the same order.

**Unary operations**

Unary operations take the top of the stack, apply the operation, and
push the result back on the stack.

UNARY_POSITIVE

   Implements "TOS = +TOS".

UNARY_NEGATIVE

   Implements "TOS = -TOS".

UNARY_NOT

   Implements "TOS = not TOS".

UNARY_INVERT

   Implements "TOS = ~TOS".

GET_ITER

   Implements "TOS = iter(TOS)".

GET_YIELD_FROM_ITER

   If "TOS" is a *generator iterator* or *coroutine* object it is left
   as is.  Otherwise, implements "TOS = iter(TOS)".

   New in version 3.5.

**Binary operations**

Binary operations remove the top of the stack (TOS) and the second
top-most stack item (TOS1) from the stack.  They perform the
operation, and put the result back on the stack.

BINARY_POWER

   Implements "TOS = TOS1 ** TOS".

BINARY_MULTIPLY

   Implements "TOS = TOS1 * TOS".

BINARY_MATRIX_MULTIPLY

   Implements "TOS = TOS1 @ TOS".

   New in version 3.5.

BINARY_FLOOR_DIVIDE

   Implements "TOS = TOS1 // TOS".

BINARY_TRUE_DIVIDE

   Implements "TOS = TOS1 / TOS".

BINARY_MODULO

   Implements "TOS = TOS1 % TOS".

BINARY_ADD

   Implements "TOS = TOS1 + TOS".

BINARY_SUBTRACT

   Implements "TOS = TOS1 - TOS".

BINARY_SUBSCR

   Implements "TOS = TOS1[TOS]".

BINARY_LSHIFT

   Implements "TOS = TOS1 << TOS".

BINARY_RSHIFT

   Implements "TOS = TOS1 >> TOS".

BINARY_AND

   Implements "TOS = TOS1 & TOS".

BINARY_XOR

   Implements "TOS = TOS1 ^ TOS".

BINARY_OR

   Implements "TOS = TOS1 | TOS".

**In-place operations**

In-place operations are like binary operations, in that they remove
TOS and TOS1, and push the result back on the stack, but the operation
is done in-place when TOS1 supports it, and the resulting TOS may be
(but does not have to be) the original TOS1.

INPLACE_POWER

   Implements in-place "TOS = TOS1 ** TOS".

INPLACE_MULTIPLY

   Implements in-place "TOS = TOS1 * TOS".

INPLACE_MATRIX_MULTIPLY

   Implements in-place "TOS = TOS1 @ TOS".

   New in version 3.5.

INPLACE_FLOOR_DIVIDE

   Implements in-place "TOS = TOS1 // TOS".

INPLACE_TRUE_DIVIDE

   Implements in-place "TOS = TOS1 / TOS".

INPLACE_MODULO

   Implements in-place "TOS = TOS1 % TOS".

INPLACE_ADD

   Implements in-place "TOS = TOS1 + TOS".

INPLACE_SUBTRACT

   Implements in-place "TOS = TOS1 - TOS".

INPLACE_LSHIFT

   Implements in-place "TOS = TOS1 << TOS".

INPLACE_RSHIFT

   Implements in-place "TOS = TOS1 >> TOS".

INPLACE_AND

   Implements in-place "TOS = TOS1 & TOS".

INPLACE_XOR

   Implements in-place "TOS = TOS1 ^ TOS".

INPLACE_OR

   Implements in-place "TOS = TOS1 | TOS".

STORE_SUBSCR

   Implements "TOS1[TOS] = TOS2".

DELETE_SUBSCR

   Implements "del TOS1[TOS]".

**Coroutine opcodes**

GET_AWAITABLE

   Implements "TOS = get_awaitable(TOS)", where "get_awaitable(o)"
   returns "o" if "o" is a coroutine object or a generator object with
   the CO_ITERABLE_COROUTINE flag, or resolves "o.__await__".

GET_AITER

   Implements "TOS = get_awaitable(TOS.__aiter__())".  See
   "GET_AWAITABLE" for details about "get_awaitable"

GET_ANEXT

   Implements "PUSH(get_awaitable(TOS.__anext__()))".  See
   "GET_AWAITABLE" for details about "get_awaitable"

BEFORE_ASYNC_WITH

   Resolves "__aenter__" and "__aexit__" from the object on top of the
   stack.  Pushes "__aexit__" and result of "__aenter__()" to the
   stack.

SETUP_ASYNC_WITH

   Creates a new frame object.

**Miscellaneous opcodes**

PRINT_EXPR

   Implements the expression statement for the interactive mode.  TOS
   is removed from the stack and printed.  In non-interactive mode, an
   expression statement is terminated with "POP_TOP".

BREAK_LOOP

   Terminates a loop due to a "break" statement.

CONTINUE_LOOP(target)

   Continues a loop due to a "continue" statement.  *target* is the
   address to jump to (which should be a "FOR_ITER" instruction).

SET_ADD(i)

   Calls "set.add(TOS1[-i], TOS)".  Used to implement set
   comprehensions.

LIST_APPEND(i)

   Calls "list.append(TOS[-i], TOS)".  Used to implement list
   comprehensions.

MAP_ADD(i)

   Calls "dict.setitem(TOS1[-i], TOS, TOS1)".  Used to implement dict
   comprehensions.

For all of the "SET_ADD", "LIST_APPEND" and "MAP_ADD" instructions,
while the added value or key/value pair is popped off, the container
object remains on the stack so that it is available for further
iterations of the loop.

RETURN_VALUE

   Returns with TOS to the caller of the function.

YIELD_VALUE

   Pops TOS and yields it from a *generator*.

YIELD_FROM

   Pops TOS and delegates to it as a subiterator from a *generator*.

   New in version 3.3.

SETUP_ANNOTATIONS

   Checks whether "__annotations__" is defined in "locals()", if not
   it is set up to an empty "dict". This opcode is only emitted if a
   class or module body contains *variable annotations* statically.

   New in version 3.6.

IMPORT_STAR

   Loads all symbols not starting with "'_'" directly from the module
   TOS to the local namespace. The module is popped after loading all
   names. This opcode implements "from module import *".

POP_BLOCK

   Removes one block from the block stack.  Per frame, there is a
   stack of blocks, denoting nested loops, try statements, and such.

POP_EXCEPT

   Removes one block from the block stack. The popped block must be an
   exception handler block, as implicitly created when entering an
   except handler.  In addition to popping extraneous values from the
   frame stack, the last three popped values are used to restore the
   exception state.

END_FINALLY

   Terminates a "finally" clause.  The interpreter recalls whether the
   exception has to be re-raised, or whether the function returns, and
   continues with the outer-next block.

LOAD_BUILD_CLASS

   Pushes "builtins.__build_class__()" onto the stack.  It is later
   called by "CALL_FUNCTION" to construct a class.

SETUP_WITH(delta)

   This opcode performs several operations before a with block starts.
   First, it loads "__exit__()" from the context manager and pushes it
   onto the stack for later use by "WITH_CLEANUP".  Then,
   "__enter__()" is called, and a finally block pointing to *delta* is
   pushed.  Finally, the result of calling the enter method is pushed
   onto the stack.  The next opcode will either ignore it ("POP_TOP"),
   or store it in (a) variable(s) ("STORE_FAST", "STORE_NAME", or
   "UNPACK_SEQUENCE").

WITH_CLEANUP_START

   Cleans up the stack when a "with" statement block exits.  TOS is
   the context manager's "__exit__()" bound method. Below TOS are 1--3
   values indicating how/why the finally clause was entered:

   * SECOND = "None"

   * (SECOND, THIRD) = ("WHY_{RETURN,CONTINUE}"), retval

   * SECOND = "WHY_*"; no retval below it

   * (SECOND, THIRD, FOURTH) = exc_info()

   In the last case, "TOS(SECOND, THIRD, FOURTH)" is called, otherwise
   "TOS(None, None, None)".  Pushes SECOND and result of the call to
   the stack.

WITH_CLEANUP_FINISH

   Pops exception type and result of 'exit' function call from the
   stack.

   If the stack represents an exception, *and* the function call
   returns a 'true' value, this information is "zapped" and replaced
   with a single "WHY_SILENCED" to prevent "END_FINALLY" from re-
   raising the exception.  (But non-local gotos will still be
   resumed.)

All of the following opcodes use their arguments.

STORE_NAME(namei)

   Implements "name = TOS". *namei* is the index of *name* in the
   attribute "co_names" of the code object. The compiler tries to use
   "STORE_FAST" or "STORE_GLOBAL" if possible.

DELETE_NAME(namei)

   Implements "del name", where *namei* is the index into "co_names"
   attribute of the code object.

UNPACK_SEQUENCE(count)

   Unpacks TOS into *count* individual values, which are put onto the
   stack right-to-left.

UNPACK_EX(counts)

   Implements assignment with a starred target: Unpacks an iterable in
   TOS into individual values, where the total number of values can be
   smaller than the number of items in the iterable: one of the new
   values will be a list of all leftover items.

   The low byte of *counts* is the number of values before the list
   value, the high byte of *counts* the number of values after it.
   The resulting values are put onto the stack right-to-left.

STORE_ATTR(namei)

   Implements "TOS.name = TOS1", where *namei* is the index of name in
   "co_names".

DELETE_ATTR(namei)

   Implements "del TOS.name", using *namei* as index into "co_names".

STORE_GLOBAL(namei)

   Works as "STORE_NAME", but stores the name as a global.

DELETE_GLOBAL(namei)

   Works as "DELETE_NAME", but deletes a global name.

LOAD_CONST(consti)

   Pushes "co_consts[consti]" onto the stack.

LOAD_NAME(namei)

   Pushes the value associated with "co_names[namei]" onto the stack.

BUILD_TUPLE(count)

   Creates a tuple consuming *count* items from the stack, and pushes
   the resulting tuple onto the stack.

BUILD_LIST(count)

   Works as "BUILD_TUPLE", but creates a list.

BUILD_SET(count)

   Works as "BUILD_TUPLE", but creates a set.

BUILD_MAP(count)

   Pushes a new dictionary object onto the stack.  Pops "2 * count"
   items so that the dictionary holds *count* entries: "{..., TOS3:
   TOS2, TOS1: TOS}".

   Changed in version 3.5: The dictionary is created from stack items
   instead of creating an empty dictionary pre-sized to hold *count*
   items.

BUILD_CONST_KEY_MAP(count)

   The version of "BUILD_MAP" specialized for constant keys.  *count*
   values are consumed from the stack.  The top element on the stack
   contains a tuple of keys.

   New in version 3.6.

BUILD_STRING(count)

   Concatenates *count* strings from the stack and pushes the
   resulting string onto the stack.

   New in version 3.6.

BUILD_TUPLE_UNPACK(count)

   Pops *count* iterables from the stack, joins them in a single
   tuple, and pushes the result.  Implements iterable unpacking in
   tuple displays "(*x, *y, *z)".

   New in version 3.5.

BUILD_LIST_UNPACK(count)

   This is similar to "BUILD_TUPLE_UNPACK", but pushes a list instead
   of tuple.  Implements iterable unpacking in list displays "[*x, *y,
   *z]".

   New in version 3.5.

BUILD_SET_UNPACK(count)

   This is similar to "BUILD_TUPLE_UNPACK", but pushes a set instead
   of tuple.  Implements iterable unpacking in set displays "{*x, *y,
   *z}".

   New in version 3.5.

BUILD_MAP_UNPACK(count)

   Pops *count* mappings from the stack, merges them into a single
   dictionary, and pushes the result.  Implements dictionary unpacking
   in dictionary displays "{**x, **y, **z}".

   New in version 3.5.

BUILD_MAP_UNPACK_WITH_CALL(oparg)

   This is similar to "BUILD_MAP_UNPACK", but is used for "f(**x, **y,
   **z)" call syntax.  The lowest byte of *oparg* is the count of
   mappings, the relative position of the corresponding callable "f"
   is encoded in the second byte of *oparg*.

   New in version 3.5.

LOAD_ATTR(namei)

   Replaces TOS with "getattr(TOS, co_names[namei])".

COMPARE_OP(opname)

   Performs a Boolean operation.  The operation name can be found in
   "cmp_op[opname]".

IMPORT_NAME(namei)

   Imports the module "co_names[namei]".  TOS and TOS1 are popped and
   provide the *fromlist* and *level* arguments of "__import__()".
   The module object is pushed onto the stack.  The current namespace
   is not affected: for a proper import statement, a subsequent
   "STORE_FAST" instruction modifies the namespace.

IMPORT_FROM(namei)

   Loads the attribute "co_names[namei]" from the module found in TOS.
   The resulting object is pushed onto the stack, to be subsequently
   stored by a "STORE_FAST" instruction.

JUMP_FORWARD(delta)

   Increments bytecode counter by *delta*.

POP_JUMP_IF_TRUE(target)

   If TOS is true, sets the bytecode counter to *target*.  TOS is
   popped.

POP_JUMP_IF_FALSE(target)

   If TOS is false, sets the bytecode counter to *target*.  TOS is
   popped.

JUMP_IF_TRUE_OR_POP(target)

   If TOS is true, sets the bytecode counter to *target* and leaves
   TOS on the stack.  Otherwise (TOS is false), TOS is popped.

JUMP_IF_FALSE_OR_POP(target)

   If TOS is false, sets the bytecode counter to *target* and leaves
   TOS on the stack.  Otherwise (TOS is true), TOS is popped.

JUMP_ABSOLUTE(target)

   Set bytecode counter to *target*.

FOR_ITER(delta)

   TOS is an *iterator*.  Call its "__next__()" method.  If this
   yields a new value, push it on the stack (leaving the iterator
   below it).  If the iterator indicates it is exhausted TOS is
   popped, and the byte code counter is incremented by *delta*.

LOAD_GLOBAL(namei)

   Loads the global named "co_names[namei]" onto the stack.

SETUP_LOOP(delta)

   Pushes a block for a loop onto the block stack.  The block spans
   from the current instruction with a size of *delta* bytes.

SETUP_EXCEPT(delta)

   Pushes a try block from a try-except clause onto the block stack.
   *delta* points to the first except block.

SETUP_FINALLY(delta)

   Pushes a try block from a try-except clause onto the block stack.
   *delta* points to the finally block.

LOAD_FAST(var_num)

   Pushes a reference to the local "co_varnames[var_num]" onto the
   stack.

STORE_FAST(var_num)

   Stores TOS into the local "co_varnames[var_num]".

DELETE_FAST(var_num)

   Deletes local "co_varnames[var_num]".

STORE_ANNOTATION(namei)

   Stores TOS as "locals()['__annotations__'][co_names[namei]] = TOS".

   New in version 3.6.

LOAD_CLOSURE(i)

   Pushes a reference to the cell contained in slot *i* of the cell
   and free variable storage.  The name of the variable is
   "co_cellvars[i]" if *i* is less than the length of *co_cellvars*.
   Otherwise it is "co_freevars[i - len(co_cellvars)]".

LOAD_DEREF(i)

   Loads the cell contained in slot *i* of the cell and free variable
   storage. Pushes a reference to the object the cell contains on the
   stack.

LOAD_CLASSDEREF(i)

   Much like "LOAD_DEREF" but first checks the locals dictionary
   before consulting the cell.  This is used for loading free
   variables in class bodies.

STORE_DEREF(i)

   Stores TOS into the cell contained in slot *i* of the cell and free
   variable storage.

DELETE_DEREF(i)

   Empties the cell contained in slot *i* of the cell and free
   variable storage. Used by the "del" statement.

RAISE_VARARGS(argc)

   Raises an exception. *argc* indicates the number of parameters to
   the raise statement, ranging from 0 to 3.  The handler will find
   the traceback as TOS2, the parameter as TOS1, and the exception as
   TOS.

CALL_FUNCTION(argc)

   Calls a function.  The low byte of *argc* indicates the number of
   positional parameters, the high byte the number of keyword
   parameters. On the stack, the opcode finds the keyword parameters
   first.  For each keyword argument, the value is on top of the key.
   Below the keyword parameters, the positional parameters are on the
   stack, with the right-most parameter on top.  Below the parameters,
   the function object to call is on the stack.  Pops all function
   arguments, and the function itself off the stack, and pushes the
   return value.

MAKE_FUNCTION(argc)

   Pushes a new function object on the stack.  From bottom to top, the
   consumed stack must consist of values if the argument carries a
   specified flag value

   * "0x01" a tuple of default argument objects in positional order

   * "0x02" a dictionary of keyword-only parameters' default values

   * "0x04" an annotation dictionary

   * "0x08" a tuple containing cells for free variables, making a
     closure

   * the code associated with the function (at TOS1)

   * the *qualified name* of the function (at TOS)

BUILD_SLICE(argc)

   Pushes a slice object on the stack.  *argc* must be 2 or 3.  If it
   is 2, "slice(TOS1, TOS)" is pushed; if it is 3, "slice(TOS2, TOS1,
   TOS)" is pushed. See the "slice()" built-in function for more
   information.

EXTENDED_ARG(ext)

   Prefixes any opcode which has an argument too big to fit into the
   default two bytes.  *ext* holds two additional bytes which, taken
   together with the subsequent opcode's argument, comprise a four-
   byte argument, *ext* being the two most-significant bytes.

CALL_FUNCTION_VAR(argc)

   Calls a function. *argc* is interpreted as in "CALL_FUNCTION". The
   top element on the stack contains the variable argument list,
   followed by keyword and positional arguments.

CALL_FUNCTION_KW(argc)

   Calls a function. *argc* is interpreted as in "CALL_FUNCTION". The
   top element on the stack contains the keyword arguments dictionary,
   followed by explicit keyword and positional arguments.

CALL_FUNCTION_VAR_KW(argc)

   Calls a function. *argc* is interpreted as in "CALL_FUNCTION".  The
   top element on the stack contains the keyword arguments dictionary,
   followed by the variable-arguments tuple, followed by explicit
   keyword and positional arguments.

FORMAT_VALUE(flags)

   Used for implementing formatted literal strings (f-strings).  Pops
   an optional *fmt_spec* from the stack, then a required *value*.
   *flags* is interpreted as follows:

   * "(flags & 0x03) == 0x00": *value* is formatted as-is.

   * "(flags & 0x03) == 0x01": call "str()" on *value* before
     formatting it.

   * "(flags & 0x03) == 0x02": call "repr()" on *value* before
     formatting it.

   * "(flags & 0x03) == 0x03": call "ascii()" on *value* before
     formatting it.

   * "(flags & 0x04) == 0x04": pop *fmt_spec* from the stack and use
     it, else use an empty *fmt_spec*.

   Formatting is performed using "PyObject_Format()".  The result is
   pushed on the stack.

   New in version 3.6.

HAVE_ARGUMENT

   This is not really an opcode.  It identifies the dividing line
   between opcodes which don't take arguments "< HAVE_ARGUMENT" and
   those which do ">= HAVE_ARGUMENT".


Opcode collections
==================

These collections are provided for automatic introspection of bytecode
instructions:

dis.opname

   Sequence of operation names, indexable using the bytecode.

dis.opmap

   Dictionary mapping operation names to bytecodes.

dis.cmp_op

   Sequence of all compare operation names.

dis.hasconst

   Sequence of bytecodes that have a constant parameter.

dis.hasfree

   Sequence of bytecodes that access a free variable (note that 'free'
   in this context refers to names in the current scope that are
   referenced by inner scopes or names in outer scopes that are
   referenced from this scope.  It does *not* include references to
   global or builtin scopes).

dis.hasname

   Sequence of bytecodes that access an attribute by name.

dis.hasjrel

   Sequence of bytecodes that have a relative jump target.

dis.hasjabs

   Sequence of bytecodes that have an absolute jump target.

dis.haslocal

   Sequence of bytecodes that access a local variable.

dis.hascompare

   Sequence of bytecodes of Boolean operations.
