code: def tokentype(self, s):
          
          a = s[0] if len(s)>0 else ""
          b = s[1] if len(s)>1 else ""
  
          if a.isdigit() or (a in ["+","-"] and b.isdigit()):
              return self.parse_number(s)
          elif a == '"': return self.parse_string(s)
          elif a == ':': return self.parse_colon(s)
          elif a == ';': return self.parse_semicolon(s)
          else:
              return self.parse_word(s)
docs: Parses string and returns a (Tokenizer.TYPE, value) tuple.