Just FWIW, a trick that I'm planning to use for PAPER: first I make separate actual commands — `paper-foo`, `paper-bar` etc. that are each implemented as separate top-level scripts that can import only what they need. Later, the implementation of `paper foo` has the main `paper` script dynamically look up `paper-foo`. (Even a `subprocess.call` would work there but I'd like to avoid that overhead)