when was the last hospital visit until 2101 that patient 10431 was admitted via transfer from hosp/extram?
select admissions.admittime from admissions where admissions.subject_id = 10431 and admissions.admission_location = 'transfer from hosp/extram' and strftime('%y',admissions.admittime) <= '2101' order by admissions.admittime desc limit 1