Add an item to the start of a list (aka Unshift).
- list: The starting list. Be sure to set the type of the list (e.g. list of objects or list of numbers)
- item: The item to add to the front. (Be sure to set the type – e.g. if the input list is a list of numbers, then item should also be set to be a number.)
- list: Returns a new list with the added item at the front. (Be sure to set the type of the output list to match that of the input list.)