Re: Where does the code for pipeline's 'agent' live?

If it is the `agent` in declarative syntax you're after here are some starting points maybe, depending on what it is you want to learn:

Where does the code for pipeline's 'agent' live?

I'm looking at how jobs in pipelines work, but I'm having trouble searching for the code for the 'agent' tag in a pipeline. I haven't found any "Symbol" for agent, but I may not have looked in the right package yet. I understand there may be something about 'Stapler', but I'm not clear. Where