code: def getfieldidd(bch, fieldname):
      
      # print(bch)
      try:
          fieldindex = bch.objls.index(fieldname)
      except ValueError as e:
          return {}  # the fieldname does not exist
                      # so there is no idd
      fieldidd = bch.objidd[fieldindex]
      return fieldidd
docs: get the idd dict for this field
      Will return {} if the fieldname does not exist