Function cron_clock::alpha0

pub fn alpha0<T>(input: T) -> Result<(T, T), Err<T, u32>> where
    T: InputTakeAtPosition,
    <T as InputTakeAtPosition>::Item: AsChar, 

Recognizes zero or more lowercase and uppercase alphabetic characters. For ASCII strings: a-zA-Z For UTF8 strings, any alphabetic code point (ie, not only the ASCII ones)