def shared_blockchain_instance(self):
if not self._sharedInstance.instance:<EOL><INDENT>klass = self.get_instance_class()<EOL>self._sharedInstance.instance = klass(**self._sharedInstance.config)<EOL><DEDENT>return self._sharedInstance.instance<EOL>
This method will initialize ``SharedInstance.instance`` and return it.
            The purpose of this method is to have offer single default
            instance that can be reused by multiple classes.