<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _load(self):
 """ Function load. :return: file contents :raises: NotFoundError if file not found """

        if self.is_exists():
            return open(self._ref, "rb").read()
        raise NotFoundError("File %s not found" % self._ref)