Function combinedfun::consume_one_where

pub fn consume_one_where<I, E, F>(
    f: F
) -> Parser<impl ParserImpl<I, Output = I::Element, Error = E>, I> where
    I: SplitFirst + Clone,
    F: Fn(&I::Element) -> bool,
    E: ConsumeError<I>, 

Consumes the first element/character of the input, if it matches the given condition.