code: def interferometer_unitary(U):
      """InterferometerUnitary
  
      Args:
          U (array): unitary matrix
  
      Returns:
          array: symplectic transformation matrix
      """
      N = 2 * len(U)
      X = U.real
      Y = U.imag
      rows = np.arange(N).reshape(2, -1).T.flatten()
      S = np.vstack([np.hstack([X, -Y]), np.hstack([Y, X])])[:, rows][
          rows
      ]
  
      return S
  
imports: import math
  import cmath
  import numpy
  from scipy.special import factorial
  import pennylane
  from pennylane.ops import Identity
  from pennylane import Device
  from .._version import __version__
label_desc: Use image node_id 11 for calling a global function with example usage: interferometer_unitary(U) and returns: S