def most_expensive_item(price_list: List[list]) -> str: """Return the name of the most expensive item 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)

"""

please complete the function body in Python