default CustomMethodHandler compose(CustomMethodHandler other) {
      if (other == null) return this;
      return (args, memState, factory, method) -> {
        DfaValue result = this.getMethodResultValue(args, memState, factory, method);
        return result == null ? other.getMethodResultValue(args, memState, factory, method) : result;
      };
    }
default CustomMethodHandler compose(CustomMethodHandler other)