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    use std::fmt;

    use crate::{lowercase, transform};

    /// This trait defines a kebab case conversion.
    ///
    /// In kebab-case, word boundaries are indicated by hyphens.
    ///
    /// ## Example:
    ///
    /// ```rust
    /// use heck::ToKebabCase;
    ///
    /// let sentence = "We are going to inherit the earth.";
    /// assert_eq!(sentence.to_kebab_case(), "we-are-going-to-inherit-the-earth");
    /// ```
    pub trait ToKebabCase: ToOwned {
        /// Convert this type to kebab case.
        fn to_kebab_case(&self) -> Self::Owned;
    }

    impl ToKebabCase for str {
        fn to_kebab_case(&self) -> Self::Owned {
            AsKebabCase(self).to_string()
        }
    }

    /// This wrapper performs a kebab case conversion in [`fmt::Display`].
    ///
    /// ## Example:
    ///
    /// ```
    /// use heck::AsKebabCase;
    ///
    /// let sentence = "We are going to inherit the earth.";
    /// assert_eq!(format!("{}", AsKebabCase(sentence)), "we-are-going-to-inherit-the-earth");
    /// ```
    pub struct AsKebabCase<T: AsRef<str>>(pub T);

    impl<T: AsRef<str>> fmt::Display for AsKebabCase<T> {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            transform(self.0.as_ref(), lowercase, |f| write!(f, "-"), f)
        }
    }

    #[cfg(test)]
    mod tests {
        use super::ToKebabCase;

        macro_rules! t {
            ($t:ident : $s1:expr => $s2:expr) => {
                #[test]
                fn $t() {
                    assert_eq!($s1.to_kebab_case(), $s2)
                }
            };
        }

        t!(test1: "CamelCase" => "camel-case");
        t!(test2: "This is Human case." => "this-is-human-case");
        t!(test3: "MixedUP CamelCase, with some Spaces" => "mixed-up-camel-case-with-some-spaces");
        t!(test4: "mixed_up_ snake_case with some _spaces" => "mixed-up-snake-case-with-some-spaces");
        t!(test5: "kebab-case" => "kebab-case");
        t!(test6: "SHOUTY_SNAKE_CASE" => "shouty-snake-case");
        t!(test7: "snake_case" => "snake-case");
        t!(test8: "this-contains_ ALLKinds OfWord_Boundaries" => "this-contains-all-kinds-of-word-boundaries");
        #[cfg(feature = "unicode")]
        t!(test9: "XΣXΣ baﬄe" => "xσxς-baﬄe");
        t!(test10: "XMLHttpRequest" => "xml-http-request");
    }