Exercise 8.1
Given the translation scheme for the EQN language, calculate the height and depth of the input: text sub text sub text.
Suppose that for each text,
getHeight(ps, text.lexval) = 8 * ps
getDepth(ps, text.lexval) = 0
做出parse tree如下：
最后可以看到所求的$height = 80$,$depth = 4.25$
