Make it easy to throw away; you will, anyway (to mix-gurus). The problem with modules that are easy to throw away is that the hole they leave is not so easily

Make it easy to throw away; you will, anyway (to mix-gurus). The problem with modules that are easy to throw away is that the hole they leave is not so easily discarded. This negative space traces the module boundary; the interfaces between modules. The only way to throw away interfaces is to throw away...? Everything. You will, anyway.