code: func (self *_parser) Scan() (tkn token.Token, literal string, idx file.Idx) {
  	return self.scan()
  }
docs: // Scan reads a single token from the source at the current offset, increments the offset and
  // returns the token.Token token, a string literal representing the value of the token (if applicable)
  // and it's current file.Idx index.