This example demonstrates setting a variable in the host-application, and accessing that from inside the filter script.
Compile the script with go build ..
Then launch it to see that the value var, as accessed by the script
keeps changing each time the script is evaluated:
$ ./variable
The variable we received was 0
We'll keep going until we hit 20 iterations.
Script gave result false
The script set new=0
The variable we received was 1
We'll keep going until we hit 20 iterations.
Script gave result false
The script set new=4
..
^C
Similarly you'll see that the value the script set was retrieved by the host application, and also changes each iteration.