Return disk I/O statistics.

    CLI Example:

    .. code-block:: bash

        salt '*' ps.disk_io_counters

        salt '*' ps.disk_io_counters device=sda1

def disk_io_counters(device=None):
    '''
    Return disk I/O statistics.

    CLI Example:

    .. code-block:: bash

        salt '*' ps.disk_io_counters

        salt '*' ps.disk_io_counters device=sda1
    '''
    if not device:
        return dict(psutil.disk_io_counters()._asdict())
    else:
        stats = psutil.disk_io_counters(perdisk=True)
        if device in stats:
            return dict(stats[device]._asdict())
        else:
            return False