2.2.2. Hierarchical Structures
Box-and-pointer structure
Suppose we evaluate the expression (list 1 (list 2 (list 3 4))). Give the result printed by the interpreter, the corresponding box-and-pointer structure, and the interpretation of this as a tree (as in figure 2.6).

Figure 2.6: The list structure in figure 2.5 viewed as a tree.