fn to_lowercase(input: &str) -> String {
    let mut s = String::with_capacity(input.len());
    s.extend(input.chars().flat_map(|c| c.to_lowercase()));
    s
}
/// `to_lowercase` converts the given string to its lowercase form.
`to_lowercase` converts the given string to its lowercase form.
` to_lowercase ` converts the given string to its lowercase form .
fn to_lowercase(input: &str) -> String {
    let mut s = String::with_capacity(input.len());
    s.extend(input.chars().flat_map(|c| c.to_lowercase()));
    s
}
fn to_lowercase ( input : & str ) -> String { let mut s = String :: with_capacity ( input . len ( ) ) ; s . extend ( input . chars ( ) . flat_map ( | c | c . to_lowercase ( ) ) ) ; s }
`to_lowercase` converts the given string to its lowercase form.
` to_lowercase ` converts the given string to its lowercase form .
input
&str