<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_token(self, token_node_id, token_attrib='token'):
 """ given a token node ID, returns the token unicode string. Parameters token_node_id : str the ID of the token node token_attrib : str name of the node attribute that contains the token string as its value (default: token). Returns ------- token : unicode the token string """

        return self.node[token_node_id][self.ns+':'+token_attrib]