TODOs in several places in the codebase (''e.g.'', [SingleDFAEngineBuilder.java](https://github.com/melt-umn/copper/blob/2d4c34b32c61e3bfc88913e5245aedffcf2de523/src/edu.umn.cs.melt.copper.compiletime/src/main/java/edu/umn/cs/melt/copper/compiletime/srcbuilders/single/SingleDFAEngineBuilder.java#L342)) say, "Remove nonterminals from the 'validLA' sets in the parse table."