- [ ] Improve test case organization
- [ ] Implement stream support (not tested)
- [X] Implement `BigInt` support
- [X] Fully localizable number systems (e.g. custom rules for combining fragments of number words)
  - [ ] Reimplement tl-PH
- [ ] Exponential syntax support
- [ ] Optimizations for fractions
- [ ] Check invalid string inputs
- [ ] Ordinals (e.g. `twentieth`, `first`, `two millionth`)
  - [ ] Implement other `fractionType`s, implement `lazy` fractions, e.g. `0.05` => `zero point zero five`,
    will implement `ratio` (`zero and five over one hundred`) and `part` (`zero and five hundredths`)