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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 is_orthonormal(self):
 """ Compute a matrix of Hilbert-Schmidt inner products for the basis operators, and see if they are orthonormal. If they are return True, else, False. :return: True if the basis vectors represented by this OperatorBasis are orthonormal, False otherwise. :rtype: bool """

        if self._is_orthonormal is None:
            _log.debug("Testing and caching if operator basis is orthonormal")
            self._is_orthonormal = np.allclose(self.metric(), np.eye(self.dim))
        return self._is_orthonormal