code: def cartesian_to_spherical_azimuthal(x, y):
      
      y = float(y) if isinstance(y, int) else y
      phi = numpy.arctan2(y, x)
      return phi % (2 * numpy.pi)
docs: Calculates the azimuthal angle in spherical coordinates from Cartesian
      coordinates. The azimuthal angle is in [0,2*pi].
  
      Parameters
      ----------
      x : {numpy.array, float}
          X-coordinate.
      y : {numpy.array, float}
          Y-coordinate.
  
      Returns
      -------
      phi : {numpy.array, float}
          The azimuthal angle.