I'm looking at this example here htt p://sfepy.org/doc-devel/examples/diffusion/poisson_functions.html. I see how all the functions are defined out in Python space. Then they're passed to SfePy by storing them in the functions dict, but there doesn't seem to be any specific mention of which arguments are passed to these functions by SfePy. How exactly does this work? Are the same variables passed to each function?