Contents:
Tests for day20 classes.
Test LoopCounter class.
LoopCounter
Ensure that sink/broadcast module are always in default state.
Test day20 main functions.
Test part2().
part2()
Test parsing code.
Test finalize_modules().
finalize_modules()
Test get_modules.
get_modules
Test parse_line().
parse_line()
Tests for day20.