input: from typing import List
  
  def create_3d_vector_class() -> str:
      """ Create a Python class which represents a 3D Vector. The class should have an
      __init__ method to initialize the vector's coordinates x, y, z and a __str__ 
      method to return the vector in the format "(x, y, z)".
      >>> vector = create_3d_vector_class()
      >>> vector.__name__
      'Vector3D'
      >>> vec = vector(1, 2, 3)
      >>> str(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