code: @Override
    protected void visitLetContentNode(LetContentNode node) {
      String generatedVarName = node.getUniqueVarName();
      visitLetParamContentNode(node, generatedVarName);
      templateTranslationContext
          .soyToJsVariableMappings()
          .put(node.getVarName(), id(generatedVarName));
    }
docs: Generates the content of a {@code let} statement. For HTML and attribute let statements, the
  generated instructions inside the node are wrapped in a function which will be optionally
  passed to another template and invoked in the correct location. All other kinds of let/param
  statements are generated as a simple variable.