std::unordered_set<string> current_constraints(colocation_constraints_);
  const AttrSlice attrs = colocate_with_op.node()->attrs();
  std::vector<string> node_constraints;
  if (TryGetNodeAttr(attrs, kColocationAttrName, &node_constraints)) {
    for (const string& entry : node_constraints) {
      StringPiece s(entry);
      if (absl::ConsumePrefix(&s, kColocationGroupPrefix)) {