def _forward(self):
try:<EOL><INDENT>self.current_token = next(self.tokens)<EOL><DEDENT>except StopIteration:<EOL><INDENT>raise MissingTokensError("<STR_LIT>" %<EOL>self.current_pos)<EOL><DEDENT>self.current_pos += <NUM_LIT:1><EOL>
Advance to the next token.

        Internal methods, updates:
        - self.current_token
        - self.current_pos

        Raises:
            MissingTokensError: when trying to advance beyond the end of the
                token flow.