def _filter_repeating_nonalnum(phrase, length):
    """
    Check if a given phrase has non repeating alphanumeric chars
    of given length.
    Example: 'phrase $$$' with length=3 will return False
    """
    if len(phrase) > 0:
        alnum_len = length
        for t in phrase:
            if not t.is_alpha:
                alnum_len -= 1
            else:
                alnum_len = length
            if alnum_len == 0:
                return None
    return phrase