Return global menu composed from all modules menu.

    This method will compose the global menu by calling menu() function for
    module, it should be located under module_path.menu module

def menu():
    """
    Return global menu composed from all modules menu.

    This method will compose the global menu by calling menu() function for
    module, it should be located under module_path.menu module
    """
    root = MenuItem('')

    for mod in droplet.modules():
        if mod.installed:
            module_path = mod.__class__.__module__.rsplit('.', 1)[0]
            menu = import_module(module_path + '.menu')
            if menu:
                menu.menu(root)

    return root