// A SavedModel may store the name of the initialization op to run in the
// in the SignatureDef (v2) or a collection (v1). If an init_op collection
// exists, then the collection must contain exactly one op.
Status GetInitOp(const string& export_dir, const MetaGraphDef& meta_graph_def,
                 string* init_op_name) {
  const auto& sig_def_map = meta_graph_def.signature_def();
  const auto& init_op_sig_it =