import time
from datetime import datetime

# t1 = datetime.now()
# time.sleep(1.345345)
# t2 = datetime.now()
# dtmicro=t2-t1
# dtms = dtmicro.seconds * 1000 + dtmicro.microseconds//1000

tprev = datetime.now()

# while True:
tnow = datetime.now()
dtmicro = tnow - tprev
# dtms = dtmicro.seconds * 1000 + dtmicro.microseconds // 1000
dtms = dtmicro.microseconds
print(tnow, tprev, dtms)
tprev = tnow