def whitespace_token
      if md=WHITESPACE.match(@chunk)
        input = md.to_a[0]
        input.length
      else
        did_not_match
      end
    end
def whitespace_token
      if md=WHITESPACE.match(@chunk)
        input = md.to_a[0]
        input.length
      else
        did_not_match
      end
    end
Matches and consumes non-meaningful whitespace.