VerifyFDef({"add1", "add2"}, M({{"feed1"}, {"feed2"}, {"feed3"}}),
             M({{"internal_out"}, {"final_out"}}),
             {{"feed1", "add1:0"},
              {"feed2", "add1:1"},
              {"add1:sum:0", "add2:0"},
              {"feed3", "add2:1"},
              {"add1:sum:0", "internal_out"},
              {"add2:sum:0", "final_out"}},
             {});
}

//
// This does not overwrite the existing shape associated with `output`,
// but merges the input shape with the existing shape.  For example,
// setting a shape of [-1, 2] with an existing shape [2, -1] would set
// a final shape of [2, 2] based on shape merging semantics.
//
// Returns an error into `status` if:
//   * `output` is not in `graph`.
//   * An invalid shape is being set (e.g., the shape being set