Function nom::digit0

pub fn digit0<T>(input: T) -> IResult<T, T> where
    T: Slice<Range<usize>> + Slice<RangeFrom<usize>> + Slice<RangeTo<usize>>,
    T: InputIter + InputLength + AtEof,
    <T as InputIter>::RawItem: AsChar, 

Recognizes zero or more numerical characters: 0-9