input: Write a function to suggest an improvement for the given python code that calculates the sum of elements in a list. The function should return the improved code as a string.
  assert suggest_improvement("def sum_elements(arr):\n    sum_value = 0\n    for num in arr:\n        sum_value += num\n    return sum_value")=='def sum_elements(arr):\n    return sum(arr) # return sum of elements of arr with one line of code.'
  assert suggest_improvement("def sum_elements(arr):\n    sum = 0\n    for i in range(len(arr)):\n        sum = sum + arr[i]\n    return sum")=='def sum_elements(arr):\n    return sum(arr) # return sum of elements of arr with one line of code.'
  assert suggest_improvement("def sum_elements(arr):\n    return sum(arr)")=='def sum_elements(arr):\n    return sum(arr) # return sum of elements of arr with one line of code.'
  assert suggest_improvement("def sum_elements(arr):\n    total = 0\n    index = 0\n    while index < len(arr):\n        total += arr[index]\n        index += 1\n    return total")=='def sum_elements(arr):\n    return sum(arr) # return sum of elements of arr with one line of code.'
output: def suggest_improvement(code):
      return 'def sum_elements(arr):\n    return sum(arr) # return sum of elements of arr with one line of code.'