input: Write a function to compute the sum of the squares of two numbers.
  assert sum_sqr(2, 3) == 13
  assert sum_sqr(1, 1) == 2
  assert sum_sqr(0, 0) == 0
  assert sum_sqr(-2, 3) == 13
output: def sum_sqr(a, b):
      return a**2 + b**2