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    // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
    // file at the top-level directory of this distribution and at
    // http://rust-lang.org/COPYRIGHT.
    //
    // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
    // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
    // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
    // option. This file may not be copied, modified, or distributed
    // except according to those terms.

    use iter::FromIterator;

    /// Collapses all unit items from an iterator into one.
    ///
    /// This is more useful when combined with higher-level abstractions, like
    /// collecting to a `Result<(), E>` where you only care about errors:
    ///
    /// ```
    /// use std::io::*;
    /// let data = vec![1, 2, 3, 4, 5];
    /// let res: Result<()> = data.iter()
    ///     .map(|x| writeln!(stdout(), "{}", x))
    ///     .collect();
    /// assert!(res.is_ok());
    /// ```
    #[stable(feature = "unit_from_iter", since = "1.23.0")]
    impl FromIterator<()> for () {
        fn from_iter<I: IntoIterator<Item=()>>(iter: I) -> Self {
            iter.into_iter().for_each(|()| {})
        }
    }

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