From my original comment: > what supporting utilities it references, how those utilities work and what constraints they impose The responsibility isn't to mem

From my original comment: > what supporting utilities it references, how those utilities work and what constraints they impose The responsibility isn't to memorize and model every function called up and down your whole stack. Often, you don't even have full insight into that if you wanted it and of course you couldn't hold that all in your head even if you wanted to. But you don't need to. The responsibility is simply to thoroughly understand how each function you call works insofar as you're using it. You should be confident, not hopeful, that the state you've arranged for that function call is a valid state for it, you should have a informed, not incurious, sense of its general behavior characteristics (fast or slow, high or low resource demands, thread safety, etc), and you should be able to make informed predictions about what its output should like given the state you pass in. It's actual implementation will often be opaque, or at least opaque at some depth, but between the function's documentation, any access to its source, and your own insight of how something like that function would likely or necessarily implemented, you can and should be able to fully model it for the purposes of your own invocation.