input: Write a function to find the smallest number in a given list. Return the smallest number.
  assert smallestNumber([4, 5, 6, 7, 8])==4
  assert smallestNumber([1, 2, 3, 4, 5])==1
  assert smallestNumber([0, -1, 2, -3, 4])==-3
  assert smallestNumber([7, 7, 7, 7])==7
  assert smallestNumber([-10])==-10
output: def smallestNumber(lst):
      return min(lst)