We will add tree traversal iterators to the LinkedBineryTree implementation started in Lab $6,$ and then work with an expression tree.

a$.$ Make the Trea interface extend Iterable. Add the abstract methods iterator $()$ and positions $(),$ returning IteratoreE and Iterator$(1(5-2)+(4(8-(3+1))))+(9((36)-(7+2)))>>$ from the above methods $as$ the "default" iterator. Override toString$()to$ return a simple list $of$ the tree values $in$ that order.

$e.$ Recall $we$ can model $an$ arithmetic expression tree $as$ a binary tree. $In$ your driver, create a binary tree, hardcoding the following expression $as$ its nodes:

$(You$ may use $*$ instead $ofxif$ you want$)$

$(1(5-2)+(4(8-(3+1))))+(9((36)-(7+2)))$