def next_token(str, start_pos):
    """Find the next token in str string from start_pos, we return
    the token and the next blank position after the token or
    str.size if this is the last token. Tokens are delimited by
    white space."""
    look_at = str[start_pos:]
    match = re.search('\S', look_at)
    if match:
        pos = match.start()
    else:
        pos = 0
        pass
    next_nonblank_pos = start_pos + pos
    next_match = re.search('\s', str[next_nonblank_pos:])
    if next_match:
        next_blank_pos = next_nonblank_pos + next_match.start()
    else:
        next_blank_pos = len(str)
        pass
    return [next_blank_pos, str[next_nonblank_pos:next_blank_pos+1].rstrip()]
Find the next token in str string from start_pos, we return
    the token and the next blank position after the token or
    str.size if this is the last token. Tokens are delimited by
    white space.