Write event data (return data and non-return data) to file on the master.

def event_return(events):
    '''
    Write event data (return data and non-return data) to file on the master.
    '''
    if not events:
        # events is an empty list.
        # Don't open the logfile in vain.
        return
    opts = _get_options({})  # Pass in empty ret, since this is a list of events
    try:
        with salt.utils.files.flopen(opts['filename'], 'a') as logfile:
            for event in events:
                salt.utils.json.dump(event, logfile)
                logfile.write(str('\n'))  # future lint: disable=blacklisted-function
    except Exception:
        log.error('Could not write to rawdata_json file %s', opts['filename'])
        raise