code: func LocationRangeBetween(a, b *LocationRange) LocationRange {
  	if a.file != b.file {
  		panic("Cannot create a LocationRange between different files")
  	}
  	return MakeLocationRange(a.FileName, a.file, a.Begin, b.End)
  }
docs: // LocationRangeBetween returns a LocationRange containing both a and b.