input: Write a python function to find the smallest and largest numbers in a list.
  assert find_smallest_and_largest([2, 5, 3, 8, 10, 11, 9]) == (2, 11)
  assert find_smallest_and_largest([10, 20, 5, 30, 7]) == (5, 30)
  assert find_smallest_and_largest([100, 50, 25, 75, 125]) == (25, 125)
output: def find_smallest_and_largest(numbers):
      smallest = min(numbers)
      largest = max(numbers)
      return (smallest, largest)