Online PHP editor | output for UGuFv

Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.32, 8.2.0 - 8.2.28, 8.3.0 - 8.3.19, 8.4.1 - 8.4.5: string(17) "1487285080.123456" string(12) "1.4872851e+9" string(17) "1487285080.123456" string(17) "1487285080.123456"
Output for 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33: string(17) "1487285080.123456" string(15) "1487285080.1235" string(17) "1487285080.123456" string(15) "1487285080.1235"
Output for 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45: Fatal error: Class 'DateTimeImmutable' not found in /in/UGuFv on line 6
Process exited with code 255.
Output for 4.3.2 - 4.3.11, 4.4.0 - 4.4.9: Fatal error: Undefined class name 'datetimeimmutable' in /in/UGuFv on line 6
Process exited with code 255.
Output for 4.3.0 - 4.3.1: Fatal error: Undefined class name 'datetimeimmutable' in /in/UGuFv on line 6