code: def get_relation_graph(self, depth=None):
          
          url = '{}relation_graph/'.format(self.url)
          if depth is not None:
              params = {'depth': depth}
          else:
              params = {}
  
          from .sample_relation import SampleRelation
          return SampleRelation._get_iter_from_url(url, params=params, append_base_url=False)
docs: Get all `SampleRelation`s in the relation graph of the sample.
  
          :param depth: max depth of the returned graph. None retrieves the complete graph.
          :return: An iterator over the relations