expression trees the tree structure is also used to parse arithmetic and boolean expressions for examplethe expression tree for would look as followsfor slightly more complex expression( ( - )we would get the followingparsing reverse polish expression now we are going to build up tree for an expression written in postfix notation then we will calculate the result we will use simple tree implementation to keep it really simplesince we are going to grow the tree by merging smaller treeswe only need tree node implementationclass treenodedef __init__(selfdata=none)self data data self right none self left none in order to build the treewe are going to enlist the help of stack you will see why soon but for the time beinglet us just create an arithmetic expression and set up our stackexpr " *split(stack stack(