Most expensive item

Complete the example in the docstring and the body of the function.

$```$

$|$def most$\_$expensive$\_$item$($price$\_$list: List$[$list$])->$ str:

$"""$Return the name of the most expensive item in price$\_$list. If there

is a tie for the most expensive item, return the name of the item that

appears latest in price$\_$list.

Precondition: price$\_$list is a list of lists in the following format:

$[[$str$,$ int$],[$str$,$ int$],...]$

where each $2-$element list represents a name $($str$)$ and a

price $($int$)$ of an item.

price$\_$list has at least one element.

$>>>$ price$\_$list $=[["$apple$",1],["$sugar$",5],["$mango$",3],$

$...["$coffee$",9],["$trail mix", $6]]$

$>>>$ most$\_$expensive$\_$item$($price$\_$list$)$

$???$

$""`"$

$```$