return d['read_history'][period] && BwDrawer.parseTime(d['read_history'][period].first) &&
d['write_history'][period] && BwDrawer.parseTime(d['write_history'][period].first);
});
return d['read_history'][period] && BwDrawer.parseTime(d['read_history'][period].first) &&
d['write_history'][period] && BwDrawer.parseTime(d['write_history'][period].first);
});