def steem_instance(self):
        ''' Returns the steem instance if it already exists
        otherwise uses the goodnode method to fetch a node
        and instantiate the Steem class.
        '''
        if self.s:
            return self.s
        for num_of_retries in range(default.max_retry):
            node = self.util.goodnode(self.nodes)
            try:
                self.s = Steem(keys=self.keys, 
                    nodes=[node])
            except Exception as e:
                self.util.retry("COULD NOT GET STEEM INSTANCE", 
                    e, num_of_retries, default.wait_time)
                self.s = None
            else:
                return self.s
        return False
Returns the steem instance if it already exists
        otherwise uses the goodnode method to fetch a node
        and instantiate the Steem class.