what is patient 44848's maximum value of metamyelocytes in 04/this year?
select max(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 44848 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'metamyelocytes' ) and datetime(labevents.charttime,'start of year') = datetime(current_time,'start of year','-0 year') and strftime('%m',labevents.charttime) = '04'