Function sexpy::head

pub fn head<'a, O1, F>(
    head_tag: &'a str, 
    inner: F
) -> impl Fn(&'a str) -> IResult<&'a str, O1, VerboseError<&'a str>> where
    F: Fn(&'a str) -> IResult<&'a str, O1, VerboseError<&'a str>>, 

Parses a head pattern. Takes a string head_tag and a parser, inner and creates a parser for [head tag inner]