input: Write a function to calculate the average of a list of positive integers and return the result as a float. If the list is empty, return 0. The function should handle any number of positive integers in the list.
  assert your_function([1, 5, 6, 7, 8])==5.4
  assert your_function([10, 20, 30, 40, 50])==30.0
  assert your_function([])==0
  assert your_function([4])==4.0
  assert your_function([3, 5, 7, 3, 5])==4.6
output: def your_function(numbers):
      if not numbers:
          return 0
      return sum(numbers) / len(numbers)