input: 
  class CreateVector3D:
      """Creates a Python class named Vector3D which represents a 3D Vector.
      The class should have an __init__ method to initialize the coordinates (x, y, z) and
      a __str__ method to return a string representation of the vector.
  
      >>> v = Vector3D(1, 2, 3)
      >>> str(v)
      '(1, 2, 3)'
      """
  
output:     
      def __init__(self, x, y, z):
          self.x = x
          self.y = y
          self.z = z
  
      def __str__(self):
          return f'({self.x}, {self.y}, {self.z})'
  