input: Write a function to calculate the sum of a list of numbers. The function should take a list of numbers as input and return the sum of the elements in the list.
  assert sum_list([1, 2, 3, 4, 5])==15
  assert sum_list([10, 20, 30])==60
  assert sum_list([-1, -2, -3, -4, -5])==-15
  assert sum_list([])==0
output: def sum_list(numbers):
      return sum(numbers)