docs: def species_list(what_list):
      '''
      provide default lists of elements to plot.
  
      what_list : string
          String name of species lists provided.
  
          If what_list is "CNONe", then C, N, O and some other light
          elements.
  
          If what_list is "s-process", then s-process indicators.
  
      '''
      if what_list is "CNONe":
          list_to_print = ['H-1','He-4','C-12','N-14','O-16','Ne-20']
      elif what_list is "sprocess":
          list_to_print = ['Fe-56','Ge-70','Zn-70','Se-76','Kr-80','Kr-82','Kr-86','Sr-88','Ba-138','Pb-208']
      elif what_list is "burn_stages":
          list_to_print = ['H-1','He-4','C-12','O-16','Ne-20','Si-28']
      elif what_list is "list_marco_1":
          list_to_print = ['C-12','O-16','Ne-20','Ne-22','Na-23','Fe-54','Fe-56','Zn-70','Ge-70','Se-76','Kr-80','Kr-82','Sr-88','Y-89','Zr-96','Te-124','Xe-130','Xe-134','Ba-138']
  
      return list_to_print