$1.$ Add a method in $$AVL$\_$tree.h$$ as follows. $(35$ pts$)$

void range$\_$search$($const Record &r$1,$ const Record &r$2,$ vector &results$)$

const;

The method takes two input parameters r$1$ and r$2,$ and one output parameter results. It requires r r$2.$ The method finds all the records that are between r$1$ and r$2$ in the AVL tree $($including r$1$ and r$2),$ and returns them in results. The output results is empty if no record is found within the range.