input: Develop a Python function that determines if a given number can be expressed as the sum of two square numbers.
  assert sum_two_squares(25) == True
  assert sum_two_squares(24) == False
  assert sum_two_squares(17) == True
output:     import math
      for i in range(int(math.sqrt(number)) + 1):
          j = math.sqrt(number - i * i)
          if j == int(j):
              return True
      return False