input: Write a python function to find the average of a list of numbers.
  assert find_average([1, 2, 3, 4, 5]) == 3.0
  assert find_average([10, 20, 30, 40, 50]) == 30.0
  assert find_average([5, 15, 25, 35, 45]) == 25.0
output: def find_average(numbers):
      if not numbers:
          return 0
      return sum(numbers) / len(numbers)