code: def _parse_marc_code(field):
      
      field = str(field)
      if len(field) < 4:
          raise Exception('Wrong field code: %s' % field)
      else:
          field += '__'
      tag = field[0:3]
      ind1 = field[3].replace('_', '')
      ind2 = field[4].replace('_', '')
      return tag, ind1, ind2
docs: Parse marc field and return default indicators if not filled in.