How can I create a variable in Python that is shared by all instances of the object?

I want to create a variable in Python that is shared by all instances of object.

    class myobj:
      shared = []
      
      def add(item):
         self.shared.append(item)
    
      def get():
         return self.shared

    item = myobj()
    item.add("Hello")
    
    item2 = myobj()
    item.add("Dave")

    item.get()  # this should return [Hello, Dave]
    item2.get() # this also should return [Hello, Dave]

I can't use external services such as memcached or database.
How can I create a variable in Python that is shared by all instances of the object?
===


I want to create a variable in Python that is shared by all instances of object.

    class myobj:
      shared = []
      
      def add(item):
         self.shared.append(item)
    
      def get():
         return self.shared

    item = myobj()
    item.add("Hello")
    
    item2 = myobj()
    item.add("Dave")

    item.get()  # this should return [Hello, Dave]
    item2.get() # this also should return [Hello, Dave]

I can't use external services such as memcached or database.