input: Write a function to calculate the sum of squares of all numbers in the given array of integers. If the array is empty, return 0.
  assert sum_squares([2, 3, 4])==29
  assert sum_squares([1, 1, 1])==3
  assert sum_squares([0])==0
  assert sum_squares([])==0
  assert sum_squares([-1, -2, 3])==14
output: def sum_squares(arr):
      return sum(x**2 for x in arr)