input: Write a python function to find the smallest, largest, and average values of a list.
  assert smallest_of_list([1, 2, 3, 4, 5]) == 1
  assert largest_of_list([1, 2, 3, 4, 5]) == 5
  assert avg_of_list([1, 2, 3, 4, 5]) == 3.0
  assert smallest_of_list([10, 20, 30, 5, 15]) == 5
  assert largest_of_list([10, 20, 30, 5, 15]) == 30
  assert avg_of_list([10, 20, 30, 5, 15]) == 16.0
output: def smallest_of_list(lst):
      return min(lst)
  
  def largest_of_list(lst):
      return max(lst)
  
  def avg_of_list(lst):
      return sum(lst) / len(lst)