This example demonstrates setting a variable in the host-application, and
accessing that from inside the filter script.
Usage
Compile the script with go build ..
Then launch it to see that the value time, as accessed by the script
keeps changing each time the script is evaluated:
$ ./variable
The time is 1569264364
Yay!
Script gave result false
The time is 1569264365
Yay!
Script gave result false
The time is 1569264366
Yay!
Script gave result false
^C