import re


def word_tokenize(sent):
    """Tokenize a sententence

    Args:
        sent: the sentence need to be tokenized

    Returns:
        list: words in the sentence
    """

    # treat consecutive words or special punctuation as words
    pat = re.compile(r"[\w]+|[.,!?;|]")
    if isinstance(sent, str):
        return pat.findall(sent.lower())
    else:
        return []