1. Develop the function count-a-vowel. Then test the complete count-vowels program.
2. At the end of intermezzo 5, we could have defined count-vowels as shown in figure 120. This version does not use vector-set!, but constructs the vector directly using build-vector. Measure the performance difference between count-vowels-bv and count-vowels. Hint: Define a function that generates a large list of random letters (with, say, 5,000 or 10,000 items).
Explain the performance difference between count-vowels-bv and count-vowels. Does the explanation reflect the measured difference? What does this suggest concerning the vector-set! operation?