Smallest with a heap

Write smallest(nums) that returns the smallest number in a non-empty list, without changing the list. min would do it; the point here is practice with heapq. Remember that heapify rearranges the list it is given, so if you use it, work on a copy.

smallest([40, 25, 2.5])  ->  2.5

import heapq

def smallest(nums):
    ...