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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _check_initialized(self):
 """Internal helper to check for uninitialized properties. Raises: BadValueError if it finds any. """

    baddies = self._find_uninitialized()
    if baddies:
      raise datastore_errors.BadValueError(
          'Entity has uninitialized properties: %s' % ', '.join(baddies))