design pattern quick reference @abc abstractmethod def _step_ (self)pass @abc abstractmethod def _step_ (self)pass @abc abstractmethod def _step_ (self)pass class concreteimplementationclass(templateabstractbaseclass)def _step_ (self)pass def _step_ (self)pass def _step_ (self)pass visitor visitor py import abc class visitable(object)def accept(selfvisitor)visitor visit(selfclass compositevisitable(visitable)def __init__(selfiterable)self iterable iterable def accept(selfvisitor)for element in self iterableelement accept(visitorvisitor visit(self