code: def get_contradictory_pairs(graph: BELGraph) -> Iterable[Tuple[BaseEntity, BaseEntity]]:
      
      for u, v in graph.edges():
          if pair_has_contradiction(graph, u, v):
              yield u, v
docs: Iterates over contradictory node pairs in the graph based on their causal relationships
      
      :return: An iterator over (source, target) node pairs that have contradictory causal edges