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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 noisy_operation(self, operation: 'cirq.Operation') -> 'cirq.OP_TREE': """Adds noise to an individual operation. Args: operation: The operation to make noisy. Returns: An OP_TREE corresponding to the noisy operations implementing the noisy version of the given operation. """

        if not hasattr(self.noisy_moments, '_not_overridden'):
            return self.noisy_moments([ops.Moment([operation])],
                                      operation.qubits)

        if not hasattr(self.noisy_moment, '_not_overridden'):
            return self.noisy_moment(ops.Moment([operation]), operation.qubits)

        assert False, 'Should be unreachable.'