static inline Signature getTombstoneKey() { return {nullptr}; }
    static unsigned getHashValue(Signature val) {
      return llvm::hash_combine_range(val.begin(), val.end());
    }
    static bool isEqual(Signature LHS, Signature RHS) {
      if (RHS == getEmptyKey()) return LHS == getEmptyKey();
      if (RHS == getTombstoneKey()) return LHS == getTombstoneKey();
      if (LHS.size() != RHS.size()) return false;

            /*op=*/DenseMapInfo<mlir::Operation*>::getEmptyKey()};
  }

  static mlir::TF::ResourceHandle getTombstoneKey() {
    return {/*container=*/"", /*name=*/"", /*device=*/"",
            /*op=*/DenseMapInfo<mlir::Operation*>::getTombstoneKey()};
  }

  static unsigned getHashValue(
      const mlir::TF::ResourceHandle& resource_handle) {