input: 
  from typing import List
  
  def create_3d_vector_class(definitions: List[str]) -> str:
      """Given a list of definitions, provide a Python class definition that represents a 3D Vector.
      The class should have an initializer that takes three arguments (x, y, and z), each representing the 
      coordinates of the vector. It should also include a __str__ method that returns the vector in the 
      format "(x, y, z)".
      >>> create_3d_vector_class(['x=3', 'y=4', 'z=5'])
      "class Vector3D:\n    def __init__(self, x, y, z):\n        self.x = x\n        self.y = y\n        self.z = z\n    \n    def __str__(self):\n        return '(' + str(self.x) + ', ' + str(self.y) + ', ' + str(self.z) + ')'"
      """
  
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) + ')'