vspipe: passing arguments to script

[kypec]

In vspipe documentation, there is mentioned --arg key=value switch that should allow passing dynamic parameters to processed script. However, I couldn't find any example or real use case of this feature. What syntax should be used to write such key placeholder in actual VapourSynth script?
Please provide some examples :thanks:

[kypec]

Many thanks HolyWu, much appreciated. Well, I figured out (about 1 hour after posting the question) that probably those parameters are regular variables in script but thanks for noting byte casting necessity explicitly.