code: def angular_separation(self, lonp1, latp1, lonp2, latp2):
          
          # Call the module-level function
          return angular_separation(lonp1, latp1, lonp2, latp2)
docs: Compute the angles between lon / lat points p1 and p2 given in radians.
          On the unit sphere, this also corresponds to the great circle distance.
          p1 and p2 can be numpy arrays of the same length.
  
          This method simply calls the module-level function of the same name.
          Consider using the module function instead, as this method may be
          deprecated in favor of that function. For now, this method is
          retained to avoid issues with the Jupyter notebooks.