Function parse_arg::match_arg

pub fn match_arg<T: ParseArg, S: AsRef<OsStr>, I>(
    name: &str, 
    arg: S, 
    next: I
) -> Option<Result<T, ValueError<<T as ParseArg>::Error>>> where
    I: IntoIterator,
    I::Item: Arg, 

Checks whether given arg matches the name or begins with name= and parses it appropriately.

In case arg is equal to name, the next argument is pulled from next iterator and parsed using the most efficient method. In case arg begins with name=, it strips the name= prefix and parses the rest.

Note: due to a limitation of std, Windows implementation is slower than Unix one in name= case. The difference is one-two allocations (depending on parsed type). This probably won't be noticable for the user.