`crystal.py` parses the ROM into classes and objects. It prmarily parses map headers, "second" map headers, map event headers, map script headers, map triggers, map "callbacks", map blockdata, xy triggers, warps, people-events, texts and scripts. The purpose of the file is to parse the ROM into python and then spit it back out with the global `to_asm()` method.
Note: throughout these examples it is possible to use `reload(crystal)` instead of `import crystal`. Once the module is loaded a first time, it must be reloaded if the file changes and the updates are desired.
After running those lines, `cp extras/output.asm main.asm` and run `git diff main.asm` to confirm that changes to `main.asm` have occurred. To test whether or not the newly inserted ASM compiles into the same ROM, use: `make clean && make`. This will complain very loudly if something is broken.