docs: def angleDiff(angle1, angle2, take_smaller=True):
      """
      smallest difference between 2 angles
      code from http://stackoverflow.com/questions/1878907/the-smallest-difference-between-2-angles
      """
      a = np.arctan2(np.sin(angle1 - angle2), np.cos(angle1 - angle2))
      if isinstance(a, np.ndarray) and take_smaller:
          a = np.abs(a)
          # take smaller of both possible angles:
          ab = np.abs(np.pi - a)
          with np.errstate(invalid='ignore'):
              i = a > ab
          a[i] = ab[i]
      return a