import textwrap


def ssplit(str_, length=420):
    """
    Splits a into multiple lines with a maximum length, without
    breaking words.

    :param str_: The string to split.
    :param length: Maximum line length.
    """
    buf = list()
    for line in str_.split('\n'):
        buf.extend(textwrap.wrap(line.rstrip('\r'), length))
    return buf