code: def get_choices_for(self, field):
          
          choices = self._fields[field].choices
          if isinstance(choices, six.string_types):
              return [(d['value'], d['name']) for d in self._choices_manager.get_all(choices)]
          else:
              return choices
docs: Get the choices for the given fields.
  
          Args:
              field (str): Name of field.
  
          Returns:
              List of tuples. [(name, value),...]