Writes a file to disk

def _write_file(folder, filename, data):
    '''
    Writes a file to disk
    '''
    path = os.path.join(folder, filename)
    if not os.path.exists(folder):
        msg = '{0} cannot be written. {1} does not exist'.format(filename, folder)
        log.error(msg)
        raise AttributeError(six.text_type(msg))
    with salt.utils.files.fopen(path, 'w') as fp_:
        fp_.write(salt.utils.stringutils.to_str(data))

    return 0