Python Docstring: how to document a function that returned an other function?

Question

I do Flask app. How to document a function that returned an other function?

@mod.route('/report')
def function():
    """"
    Function call 'function_2' for display report
    :return: function_2
    :rtype: 
    """
    return function_2(data=data, template="/report.html")