input: def create_3d_vector_class():
      """This function generates a Python class representing a 3D Vector, 
      containing an initialization method with x, y, and z coordinates, 
      and a method for converting the vector to a string format.
      >>> vec = create_3d_vector_class().__new__(Vector3D, 1, 2, 3)
      >>> vec.__init__(1, 2, 3)
      >>> print(vec)
      (1, 2, 3)
      """
  
      class Vector3D:
          def __init__(self, x, y, z):
              self.x = x
              self.y = y
              self.z = z
  
          def __str__(self):
              return "(" + str(self.x) + ", " + str(self.y) + ", " + str(self.z) + ")"
      
      return Vector3D
output:     
      class Vector3D:
          def __init__(self, x, y, z):
              self.x = x
              self.y = y
              self.z = z
  
          def __str__(self):
              return "(" + str(self.x) + ", " + str(self.y) + ", " + str(self.z) + ")"
      
      return Vector3D
  