code: def value_indexes_mapping(l):
      '''
          from elist.elist import *
          from elist.jprint import pobj
          l = ['a','b','b','a','c','b']
          desc = value_indexes_mapping(l)
          pobj(desc)
      '''
      pt = copy.deepcopy(l)
      desc = {}
      vset = set({})
      for v in pt:
          vset.add(v)
      for v in vset:
          desc[v] = []
      for i in range(0,l.__len__()):
          desc[l[i]].append(i)
      return(descf value_indexes_mapping(l):
      '''
          from elist.elist import *
          from elist.jprint import pobj
          l = ['a','b','b','a','c','b']
          desc = value_indexes_mapping(l)
          pobj(desc)
      '''
      pt = copy.deepcopy(l)
      desc = {}
      vset = set({})
      for v in pt:
          vset.add(v)
      for v in vset:
          desc[v] = []
      for i in range(0,l.__len__()):
          desc[l[i]].append(i)
      return(desc)
docs: from elist.elist import *
          from elist.jprint import pobj
          l = ['a','b','b','a','c','b']
          desc = value_indexes_mapping(l)
          pobj(desc)