input: Write a function to compute the product of a list of numbers.
  assert product_of_list([1, 2, 3, 4]) == 24
  assert product_of_list([5, 6, 7]) == 210
  assert product_of_list([10, 20, 30]) == 6000
output: def product_of_list(numbers):
      product = 1
      for number in numbers:
          product *= number
      return product