t1_secs = s1 + 60 * (m1 + 60 * h1)
t2_secs = s2 + 60 * (m2 + 60 * h2)
return t2_secs - t1_secs
diff_times_in_seconds(datetime.datetime.strptime('13:23:34', '%H:%M:%S').
    time(), datetime.datetime.strptime('14:02:39', '%H:%M:%S').time())
subtract two times in python