private static @NotNull ChainVariable replaceFnVariable(@NotNull String oldName,
                                                          @NotNull ChainVariable variable,
                                                          @NotNull ChainVariable replacement) {
    return oldName.equals(variable.getName()) ? replacement : variable;
  }
private static @NotNull ChainVariable replaceFnVariable(@NotNull String oldName,
                                                          @NotNull ChainVariable variable,
                                                          @NotNull ChainVariable replacement)