Assert the given option is selected from the select with label
    (recommended), name or id.

    If multiple selections are supported other options may be selected.

def assert_single_selected(self, option_name, select_name):
    """
    Assert the given option is selected from the select with label
    (recommended), name or id.

    If multiple selections are supported other options may be selected.
    """
    option = find_option(world.browser, select_name, option_name)
    assert option.is_selected(), "Option should be selected."