Create a function that returns True if the first list is a subset of the second. Return False otherwise.
is_subset([3, 2, 5], [5, 3, 7, 9, 2]) ➞ True
is_subset([8, 9], [7, 1, 9, 8, 4, 5, 6]) ➞ True
is_subset([1, 2], [3, 5, 9, 1]) ➞ False
Both lists will contain only unique values.