sclass TokenRangeInterpretations<A> {
  new DoubleKeyedMap<Int, Int, A> interpretations;
  
  A getInterpretation(IntRange tokenRange) {
    ret tokenRange == null ? null : interpretations.get(tokenRange.start, tokenRange.end);
  }
  
  void setInterpretation(IntRange tokenRange, A a) {
    interpretations.put(tokenRange.start, tokenRange.end, a);
  }
}

Began life as a copy of #1027942