Simple word tokenizer that returns a list of non-empty words in lowercase

SimpleWordTokenizer.py

def simpleWordTokenizer(string):
    """ A simple (for-comprehension) implementation  of input string tokenization
    Args:
        string (str): input string
    Returns:
        list: a list of tokens in lowercase and no empty strings
    """
    return [x for x in re.split(split_regex, string.lower()) if x]

starWarsDarkSide = 'Only at the end do you realize the power of the Dark Side.'
print simpleWordTokenizer(starWarsDarkSide) # should give ['only', 'at', 'the', 'end', 'do', 'you', 'realize', 'the', 'power', ...]