code: def inv_mix_columns(state):
      
      state = state.reshape(4, 4, 8)
      return fcat(
          multiply(IMA, state[0]),
          multiply(IMA, state[1]),
          multiply(IMA, state[2]),
          multiply(IMA, state[3]),
      )
docs: Transformation in the Inverse Cipher that is the inverse of MixColumns().