code: def check_zip(self, token):
          
          if self.zip is None:
              # print "last matched", self.last_matched
              if self.last_matched is not None:
                  return False
                  # print "zip check", len(token) == 5, re.match(r"\d{5}", token)
              if len(token) == 5 and re.match(r"\d{5}", token):
                  self.zip = self._clean(token)
  
                  return True
          return False
docs: Returns true if token is matches a zip code (5 numbers). Zip code must be the last token in an address (minus anything
          removed during preprocessing such as --2 units.