def chunkInto64CharsPerLine(data, separator=b'\n'):
    """Chunk **data** into lines with 64 characters each.

    :param basestring data: The data to be chunked up.
    :keyword basestring separator: The character to use to join the chunked
        lines. (default: ``b'\n'``)
    :rtype: basestring
    :returns: The **data**, as a string, with 64 characters (plus the
        **separator** character), per line.
    """
    chunked = []

    while len(data) > 0:
        chunked.append(data[:64])
        data = data[64:]

    lines = separator.join(chunked)

    return lines