input: Write a python function to calculate the sum of a list of numbers.
  assert calculate_sum([2, 7, 4, 10, 5]) == 28
  assert calculate_sum([1, 2, 3, 4, 5]) == 15
  assert calculate_sum([10, 20, 30, 40]) == 100
output: def calculate_sum(numbers):
      return sum(numbers)