def _is_whitespace(char):
    """
    Checks whether `chars` is a whitespace character.
    """
    # \t, \n, and \r are technically contorl characters but we treat them
    # as whitespace since they are generally considered as such.
    if char == " " or char == "\t" or char == "\n" or char == "\r":
        return True
    cat = unicodedata.category(char)
    if cat == "Zs":
        return True
    return False
Checks whether `chars` is a whitespace character.
ptstructure/vqa/pytorchnlp/transformers/tokenizer_utils.py