and recursive calls. Again, no loops! Do not use any builtin string functions other than len, or the string operators and [:] for indexing and slicing, respectively. 3. (9 points) Write a recursive function called negative.sum with a single parameter L, which is a list of integers. The function returns True if L contains a pair of integers whose sum is negative and False otherwise. The base case occurs when the list has exactly two integers (since it doesn't make sense to talk about a "pair" of integers for lists with fewer than two elements). For example, negative sum should return False for the list [12, 8, 10, -5] and True for the list [12, 3, 8, 10, -5]. Your function should consist only of the base case and the recursive calls. No loops should be used in the implementation. You are not allowed to use any builtin functions other than len (for the base case). In addition, you are only allowed to use the index operator C, the slice operator :, and list concatenation