(PHP 7 >= 7.1.0, PHP 8)
pcntl_async_signals — Enable/disable asynchronous signal handling or return the old setting
   If the enable parameter is null,
   pcntl_async_signals() returns whether asynchronous signal
   handling is enabled. Otherwise, asynchronous signal handling is enabled or
   disabled.
  
enableWhether asynchronous signal handling should be enabled.
   When used as getter (enable parameter is null) it returns
   whether asynchronous signal handling is enabled. When used as setter (enable
   parameter is not null), it returns whether asynchronous signal
   handling was enabled before the function call.
  
| Version | Description | 
|---|---|
| 8.0.0 | enableis nullable now. | 
