Prolog uses general trees, not binary trees.   An example is _x000D_
_x000D_
         a(b,c,d(e,f,g))   where root a has 3 kids, as does kid d._x000D_
_x000D_
     It is possible to define both preorder and postorder for general trees, _x000D_
     although inorder of course makes no sense._x000D_
_x000D_
     For this assignment we are interested in postorder, which is defined as_x000D_
     follows:_x000D_
_x000D_
       to 'visit' a tree in postorder, _x000D_
          you visit the subtrees of the root, in left to right order,_x000D_
          in postorder, and then you visit the root_x000D_
_x000D_
     Thus the example above would yield the following postorder traversal:_x000D_
_x000D_
            b c e f g d a_x000D_
_x000D_
     _x000D_
     Write Prolog code which will perform a postorder traversal of a Prolog_x000D_
     tree constant.   Hint: you might use 'univ', or its cousins._x000D_
_x000D_
     Sample dialog:_x000D_
     _x000D_
     ?- postorder(a(b,c,d(e,f,g)))._x000D_
     b c e f g d a    true