code: def parse(cls, parser, text, pos):
          
          match = cls.regex.match(text)
          if match:
              # Check if match is is not in the grammar of the specific keyword class.
              if match.group(0).lower() not in cls.grammar:
                  result = text, SyntaxError(repr(match.group(0)) + " is not a member of " + repr(cls.grammar))
              else:
                  result = text[len(match.group(0)):], cls(match.group(0))
          else:
              result = text, SyntaxError("expecting " + repr(cls.__name__))
          return result
docs: Checks if terminal token is a keyword after lower-casing it.