## CSci 1301: Lab 5

You may work in groups of 2 or 3 (preferred) or individually.

#### What to submit

At the end of the lab please send me and your group partner(s) all your Scheme files as e-mail attachments. My e-mail is elenam at morris.umn.edu. The subject of your e-mail must be "1301 Lab 5" followed by "Final" or "Not final", depending on whether this is a final submission or you are still working on it. If you need to finish it, make sure to set up a time with your group partner(s) to finish the lab.

#### When to submit

Due Wednesday, October 14th, at 11:59pm. If you submit the final version during the lab, you are done.

### Problem 1 (8 points)

Write a function `remove-element` that takes a list of symbols and a symbol and returns a new list that has all occurrences of the given symbol removed.
Examples:

``````
(remove-element (cons 'A (cons 'B (cons 'A (cons 'C empty)))) 'A)
;; expected value
(cons 'B (cons 'C empty))

(remove-element (cons 'A (cons 'B (cons 'A (cons 'C empty)))) 'D)
;; expected value
(cons 'A (cons 'B (cons 'A (cons 'C empty))))

(remove-element empty 'A)
;; expected value
empty
``````

### Problem 2: Fortune Teller (12 points)

Write a recursive function `get-nth` that takes a list and a number n > 0 and returns the element at n-th position from the start of the list. Note that the function does not use list elements and therefore should work for lists of any type (or a mix of types).
If there is no element at that position, your function must signal an error "No such element"
Note that your function will have to change both n and the list for the recursive call. It also needs two base cases.
Examples:

``````
(get-nth 2 (cons 2 (cons 3 (cons 5 (cons 7 empty)))))
;; expected value
3

(get-nth 2 (cons 4 (cons 5 empty)))
;; expected value
5

(get-nth 3 (cons 4 (cons 5 empty)))
;; expected value
get-nth: No such element
``````

When the function is done, write a function `fortune-teller`: it takes a list of "fortunes" (symbols or strings), uses the function `random` (see in-class examples) to randomly choose a position in the list, and calls `get-nth` to choose the fortune at that position. (random n) gives numbers from 0 to n-1 so you need to add 1 to the result before a call to get-nth.
For instance, if the fortunes are

``````
(cons "Today you will find something precious"
(cons "Today is not your day" empty))
``````
and (random 2) gives 0, you select the first element on the list, i.e. "Today you will find something precious".

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