code: def _compute_phasediff(cross_correlation_max):
      """
      Compute global phase difference between the two images (should be
          zero if images are non-negative).
  
      Parameters
      ----------
      cross_correlation_max : complex
          The complex value of the cross correlation at its maximum point.
      """
      return np.arctan2(
          cross_correlation_max.imag, cross_correlation_max.real
      )
  
file_path: scikit-image/skimage/registration/_phase_cross_correlation.py
imports: import itertools
  import warnings
  import numpy
  from scipy.fft import fftn, ifftn, fftfreq
  from scipy import ndimage
  from ._masked_phase_cross_correlation import _masked_phase_cross_correlation
label_desc: Use image node_id 2 for calling a global function with example usage: _compute_phasediff(cross_correlation_max) and returns: np