input: Write a function to find the minimum number in a list.
  assert min_in_list([5, 12, 3, 1, 8]) == 1
  assert min_in_list([10, 4, 2, 20, 15]) == 2
  assert min_in_list([100, 200, 300, 50, 0]) == 0
output: def min_in_list(lst):
      return min(lst)