input: Write a function to refactor the given function using Python built-in functions. The original function takes an array of numbers and returns the sum of all the numbers. The refactored function should achieve the same result using Python's built-in capabilities.
  
  
  def sum_array(array):
      '''A function that takes in an array of numbers and returns the sum of all the numbers'''
      return sum(array)
  
  assert sum_array([1, 2, 3, 4, 5])==15
  assert sum_array([-1, -2, -3, -4, -5])==-15
  assert sum_array([0, 0, 0, 0, 0])==0
  assert sum_array([])==0
  assert sum_array([10])==10
  
output: def sum_array(array):
      return sum(array)