│ Given a list of numbers, where every number shows up twice except for │ one number, find that one number. │ Example: │Input: [4, 3, 2, 4, 1, 3, 2] │Output: 1 │ │ Here’s the function signature: │def singleNumber(nums): │ # Fill this in. │print singleNumber([4, 3, 2, 4, 1, 3, 2]) │# 1 │ │ Challenge: Find a way to do this using O(1) memory.