def comma_code(items):
    """ Combines list into a string of the form item1, item2, and item 3
    Args:
        items (list): List of strings

    Returns:
        string: list items combined into a string
    """
    item_len = len(items)
    
    if item_len == 0:
        return ''
    elif item_len == 1:
        return items[0]

    return ', '.join(items[:-1]) + ', and ' + items[-1]