code: def add_child(self, child):
          
  
          rest_name = child.rest_name
          children = self.fetcher_for_rest_name(rest_name)
  
          if children is None:
              raise InternalConsitencyError('Could not find fetcher with name %s while adding %s in parent %s' % (rest_name, child, self))
  
          if child not in children:
              child.parent_object = self
              children.append(child)
docs: Add a child