How to redirect all methods of a contained class in Python?

How to implement the composition pattern? I have a class Container which has an attribute object Contained. I would like to redirect/allow access to all methods of Contained class from Container by simply calling my_container.some_contained_method(). Am I doing the right thing in the right way?

I use something like:

class Container:
   def __init__(self):
       self.contained = Contained()
   def __getattr__(self, item):
       if item in self.__dict__: # some overridden
           return self.__dict__[item] 
       else:
           return self.contained.__getattr__(item) # redirection

Background:

I am trying to build a class (Indicator) that adds to the functionality of an existing class (pandas.DataFrame). Indicator will have all the methods of DataFrame. I could use inheritance, but I am following the "favor composition over inheritance" advice (see, e.g., the answers in: python: inheriting or composition). One reason not to inherit is because the base class is not serializable and I need to serialize.

I have found this, but I am not sure if it fits my needs.