<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse_bytes(self, bytestr, isfinal=True):
 """ Parse a byte string. If the string is very large, split it in chuncks and parse each chunk with isfinal=False, then parse an empty chunk with isfinal=True. """

        with self._context():
            self.filename = None
            self.p.Parse(bytestr, isfinal)
        return self._root