docs: def fermi_fourier_trans_inverse_4(qubits):
      """The reverse fermionic Fourier transformation implemented on 4 qubits
      on a line, which maps the momentum picture to the position picture.
      Using the fast Fourier transformation algorithm, the circuit can be
      decomposed into 2-mode fermionic Fourier transformation, the fermionic
      SWAP gates, and single-qubit rotations.
  
      Args:
          qubits: list of four qubits
      """
  
      yield fswap(qubits[1], qubits[2]),
      yield fermi_fourier_trans_2(qubits[0], qubits[1])
      yield fermi_fourier_trans_2(qubits[2], qubits[3])
      yield fswap(qubits[1], qubits[2])
      yield fermi_fourier_trans_2(qubits[0], qubits[1])
      yield cirq.S(qubits[2])
      yield fermi_fourier_trans_2(qubits[2], qubits[3])
      yield fswap(qubits[1], qubits[2])