Create a function that takes an array of values and returns the first and last values in a new array.
first_last([5, 10, 15, 20, 25]) ➞ [5, 25]
first_last(["edabit", 13, nil, false, true]) ➞ ["edabit", true]
first_last([nil, 4, "6", "hello", nil]) ➞ [nil, nil]return the result.