docs: def diffs_prof(step):
      """Scaled diffusion.
  
      This computation takes sphericity into account if necessary.
  
      Args:
          step (:class:`~stagpy.stagyydata._Step`): a step of a StagyyData
              instance.
      Returns:
          tuple of :class:`numpy.array`: the diffusion and the radial position
          at which it is evaluated.
      """
      diff, rad = diff_prof(step)
      return _scale_prof(step, diff, rad), rad