code: def descendants(self, node, relations=None, reflexive=False):
          
          if reflexive:
              decs = self.descendants(node, relations, reflexive=False)
              decs.append(node)
              return decs
          g = None
          if relations is None:
              g = self.get_graph()
          else:
              g = self.get_filtered_graph(relations)
          if node in g:
              return list(nx.descendants(g, node))
          else:
              return []
docs: Returns all descendants of specified node.
  
          The default implementation is to use networkx, but some
          implementations of the Ontology class may use a database or
          service backed implementation, for large graphs.
  
  
          Arguments
          ---------
          node : str
              identifier for node in ontology
          reflexive : bool
              if true, return query node in graph
          relations : list
               relation (object property) IDs used to filter
  
          Returns
          -------
          list[str]
              descendant node IDs