def _process_loop_helper(self, node, **kwargs):
        """
        Processes a loop helper e.g. {{ loop.first }} or {{ loop.index }}
        """

        if node.attr == LOOP_HELPER_INDEX:
            self.output.write("(arguments[1] + 1)")
        elif node.attr == LOOP_HELPER_INDEX_0:
            self.output.write("arguments[1]")
        elif node.attr == LOOP_HELPER_FIRST:
            self.output.write("(arguments[1] == 0)")
        elif node.attr == LOOP_HELPER_LAST:
            self.output.write("(arguments[1] == arguments[2].length - 1)")
        elif node.attr == LOOP_HELPER_LENGTH:
            self.output.write("arguments[2].length")

        Processes a loop helper e.g. {{ loop.first }} or {{ loop.index }}
        
website/setup/jinja_to_js.py