input: Write a python function to create a string representation of a Points object.
  assert str(Points(1, 2, 3)) == "x=1, y=2, z=3"
  assert str(Points(4, 5, 6)) == "x=4, y=5, z=6"
  assert str(Points(-1, -2, -3)) == "x=-1, y=-2, z=-3"
output: def Points(x, y, z):
      class PointsClass:
          def __init__(self, x, y, z):
              self.x = x
              self.y = y
              self.z = z
  
          def __str__(self):
              return f"x={self.x}, y={self.y}, z={self.z}"
  
      return PointsClass(x, y, z)