Your Tasks

Lee has discovered what he thinks is a clever recursive strategy for printing the elements in a sequence $($string$,$ tuple, or list$).$ He reasons that he can get at the first element in a sequence using the $0$ index, and he can obtain a sequence of the rest of the elements by slicing from index $1.$ This strategy is realized in a function that expects just the sequence as an argument. If the sequence is not empty, the first element in the sequence is printed and then a recursive call is executed. On each recursive call, the sequence argument is sliced using the range $1$:$.$

Here is Lee$$s function definition:

def printAll$($seq$)$:

if seq:

print$($seq$[0])$

printAll$($seq$[1$:$])$

Write a script $($in the file testprintlist.py$)$ that tests this function and add code to trace the argument on each call. Does this function work as expected? If so$,$ how does it works, and describe any hidden costs in running it$.($LO: $7\mathrm{.}1)$

Instructions

Task $1$: Implement the printAll function.

Does this function work as expected? Do you see any hidden costs to running it$?$

Answer

Before each recursive call, the function creates a slice of its nonempty list argument. The hidden cost is that each slice produces a copy of the list, less its first item. This process requires time and memory.