Duration: P1Y2M3DT10H30M is 37017000 seconds
Seconds: 37017000 is P1Y2M3DT10H30M duration
Duration: -P120D is -10368000 seconds
Seconds: -10368000 is -P4M duration
Seconds: 1750963079 is P55Y6M10DT18H37M59S duration
Duration: P55Y6M10DT18H37M59S is 1750963079 seconds
Add should be PT0S: PT0S
Subtract should be PT0S: PT0S