<< " Expected Control edges: " << ToString(c_edges)
          << " Actual edges: " << ToString(a_edges)
          << " in fdef: " << fdef.DebugString();
    }
  }

  void VerifyFDef(const std::unordered_set<string>& nodes,
                  const std::vector<IOSpec>& inputs,
                  const std::vector<IOSpec>& outputs,
                  const std::vector<EdgeSpec>& e_edges,  // expected edges