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/// Make a string's first character lowercase
///
/// # Description
///
/// Returns a string with the first character of str lowercased if that character is alphabetic.
///
/// Note that 'alphabetic' is determined by the current locale. For instance, in the default "C"
/// locale characters such as umlaut-a (ä) will not be converted.
///
/// # Examples
///
/// Example #1 lcfirst() example
///
/// ```
/// use phpify::string::lcfirst;
///
/// let foo = "HelloWorld";
/// assert_eq!(lcfirst(foo), "helloWorld");
///
/// let bar = "HELLO WORLD!";
/// assert_eq!(lcfirst(bar), "hELLO WORLD!");
/// ```
pub fn lcfirst<S>(str: S) -> String
    where
        S: AsRef<str> {

    let mut chars = str.as_ref().chars();

    match chars.next() {
        None => String::new(),
        Some(char) => char.to_lowercase().collect::<String>() + chars.as_str(),
    }
}

#[cfg(test)]
mod tests {
    use crate::string::lcfirst;

    #[test]
    fn test() {
        assert_eq!(lcfirst("ABC"), "aBC");
        assert_eq!(lcfirst("ÄBC"), "äBC");
        assert_eq!(lcfirst("ΔΞΠ"), "δΞΠ");
    }
}