acquire method
Starts holding an assertion with options; throws when the helper
cannot be spawned (the caller warns and continues).
Implementation
@override
Future<PowerAssertionHandle> acquire(PowerAssertionOptions options) async {
final arguments = caffeinateArguments(options, pid: pid);
final process = await _launcher('caffeinate', arguments);
return ProcessPowerAssertionHandle(
process: process,
description: 'caffeinate ${arguments.join(' ')}',
);
}