I think this falls under getting the lambda and choice of function right. Likewise more complex expressions are easy to get wrong. There are implementation deta

I think this falls under getting the lambda and choice of function right. Likewise more complex expressions are easy to get wrong. There are implementation details to both you need to nail. Is it better to fail in referencing the wrong variable or calling the wrong function with the wrong (but valid) input? Which is to say if you get the implementation details wrong you’ve got the implementation wrong and notice very quickly with any halfway reasonable test.