code: def md_step_group(k):
      
  
      cbpdnmd_xstep(k)
      if mp_xrlx != 1.0:
          cbpdnmd_relax(k)
      cbpdnmd_ystep(k)
      cbpdnmd_ustep(k)
      ccmodmd_setcoef(k)
      ccmodmd_xstep(k)
      if mp_drlx != 1.0:
          ccmodmd_relax(k)
docs: Do a single iteration over cbpdn and ccmod steps that can be
      performed independently for each slice `k` of the input data set.