Create expression that selects map items identified by key range
(begin inclusive, end exclusive). If begin is nil, the range is less than end.
If end is infinity, the range is greater than equal to begin.
Expression returns selected data specified by returnType.
Create expression that selects map items identified by key range (begin inclusive, end exclusive). If begin is nil, the range is less than end. If end is infinity, the range is greater than equal to begin. Expression returns selected data specified by returnType.