code: @ForOverride
    protected SoyValue computeFunctionHelper(
        SoyJavaSourceFunction fn, List<SoyValue> args, final FunctionNode fnNode) {
      try {
        return new TofuValueFactory(fnNode, pluginInstances).computeForJava(fn, args, context);
      } catch (Exception e) {
        throw RenderException.create(
            "While computing function \"" + fnNode.toSourceString() + "\": " + e.getMessage(), e);
      }
    }
docs: Protected helper for {@code computeFunction}.
  
  @param fn The function object.
  @param args The arguments to the function.
  @param fnNode The function node. Only used for error reporting.
  @return The result of the function called on the given arguments.