message: Add __matmul__ override for using @ for LinearOperator matrix multiplication (e.g. A @ B).
diff: @@ -652,6 +652,9 @@ class LinearOperator(module.Module):
  return self._matmul(x, adjoint=adjoint, adjoint_arg=adjoint_arg)
  + def __matmul__(self, other):
  + return self.matmul(other)
  +
  def _matvec(self, x, adjoint=False):
  x_mat = array_ops.expand_dims(x, axis=-1)
  y_mat = self.matmul(x_mat, adjoint=adjoint)
  