code: def not_next(e):
      
      def match_not_next(s, grm=None, pos=0):
          try:
              e(s, grm, pos)
          except PegreError as ex:
              return PegreResult(s, Ignore, (pos, pos))
          else:
              raise PegreError('Negative lookahead failed', pos)
      return match_not_next
docs: Create a PEG function for negative lookahead.