fig the ast for ( similarlynodes for the other operators and operands can be constructed to yield the tree shown in fig to represent this in the computerwe could define one class for each type of node we'll define timesnodea plusnodeand numnode class so we can evaluate the abstract syntax treeeach node in the tree will have one eval method defined on it the code in sect defines these classesthe eval methodsand main function that builds the example tree in fig constructing asts class timesnodedef __init__(selfleftright)self left left self right right def eval(self)return self left eval(self right eval( class plusnodedef __init__(selfleftright)self left left self right right def eval(self)return self left eval(self right eval( class numnodedef __init__(selfnum)self num num def eval(self)return self num def main() numnode( numnode( plusnode( ,yt timesnode(pnumnode( )root plusnode(tnumnode( ) this copy belongs to 'acha