Problem $6$: Find Unique Elements

In this problem, we will create a function named unique$()$ that will identify the unique elements contained within a list.

The function will return a list that contains the same values as the argument list, but with duplicate values removed, and

sorted in ascending order. For example, if mylist $=[4,6,3,3,9,6,4],$ then unique$($mylist$)$ should return

$[3,4,6,9].$

Define a function named unique$()$ with a single parameter x$,$ which is expected to be a list. The function should return

a new list, containing a single occurrence of every value that appears in x$.$ The list returned should be sorted in

ascending order.

You are allowed to use the range$()$ and len$()$ functions $($if needed$)$ and the append$()$ and sort$()$ list methods, but

no other predefined functions or methods should be used. I would recommend using one or both of the following

comparison operators: in and not in