def format_list_items(items, format_string, *args, **kwargs):
    """
    Apply formatting to each item in an iterable. Returns a list.
    Each item is made available in the format_string as the 'item' keyword argument.
    example usage: ['png','svg','pdf']|format_list_items('{0}. {item}', [1,2,3]) -> ['1. png', '2. svg', '3. pdf']
    """
    return [format_string.format(*args, item=item, **kwargs) for item in items]