code: def default_channel_ops(nqubits):
      
      for gates in cartesian_product(TOMOGRAPHY_GATES.values(), repeat=nqubits):
          yield qt.tensor(*gates)
docs: Generate the tomographic pre- and post-rotations of any number of qubits as qutip operators.
  
      :param int nqubits: The number of qubits to perform tomography on.
      :return: Qutip object corresponding to the tomographic rotation.
      :rtype: Qobj