input: Write a function to calculate the sum of squares of all numbers provided in a given array. If the input array is empty, return 0.
  assert sum_squares([2, 3, 4])==29
  assert sum_squares([1, 2, 3, 4, 5])==55
  assert sum_squares([0, -1, -2])==5
  assert sum_squares([5])==25
  assert sum_squares([])==0
output: def sum_squares(arr):
      return sum(x**2 for x in arr)