Problem $4$

Because of your success implementing features in the 'user$-$feedback' module, you've decided to branch out and add a core feature to the shell. Write

a recursive function num$\_$occurrences $($filename$,$ path$)$ that counts the number of times the file filename appears in the directory pointed at by

path or any of its subdirectories. The function should return that count. If the filename OR the path do not exist, your function should return $0.$

Hint: this problem is very similar to the search $()$ and count$\_$files $()$ examples we did in class. Is there any way you can combine the approaches

of those two exercises to solve this problem?

For the example usage, assume that we're using the same directory structure that was provided as part of code$\_$samples.zip in Week $7$ of the

Content page. That is reproduced below for your convenience.

test

dubious$1.$txt

simple.py

test.txt

test$1$

dubious$2.$txt

simple.py

test.txt

test$2$

dubious$1.$txt

simple.py

test$3$

dubious$2.$txt

simple.py

test$4$

empty.txt

Sample usage is below:

$$ num$\_$occurrences$(\text{'}$

simple.py$\text{'},$ 'test'$)$

$4$

$$ num$\_$occurrences$(\text{'}$empty$.$txt$\text{'},$ 'test'$)$

$1$

$$ num$\_$occurrences$(\text{'}$

simple.py$\text{'},$ 'test$/$test$2\text{'})$

$2$

$$ num$\_$occurrences$(\text{'}$does$\_$not$\_$exist.py$\text{'},$ 'test$/$test$1\text{'})$

$0$

$$ num$\_$occurrences$(\text{'}$

simple.py$\text{'},$ 'does$\_$not$\_$exist$/$directory$\text{'})$

$0$