input: 
  from typing import List
  
  def smallestNumber(nums: List[int]) -> int:
      """ Find the smallest number in the given list of integers.
      >>> smallestNumber([4, 5, 6, 7, 8])
      4
      >>> smallestNumber([34, 56, 12, 2, 90])
      2
      """
  
output:     if not nums:
          return None
      min_num = nums[0]
      for num in nums:
          if num < min_num:
              min_num = num
      return min_num