message: Change `TF_FunctionDebugString` to return a compact function-like output.
diff: @@ -151,7 +151,7 @@ const char* TF_GraphDebugString(TF_Graph* graph, size_t* len) {
  }
  char* TF_FunctionDebugString(TF_Function* func, size_t* len) {
  - const auto& debug_str = func->fdef.DebugString();
  + const auto& debug_str = DebugString(func->fdef);
  *len = debug_str.size();
  char* ret = static_cast<char*>(malloc(*len + 1));
  memcpy(ret, debug_str.c_str(), *len + 1);
  