<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def session_login(self, user=None, passwd=None):
 """ Performs a session login by posting the auth information to the _session endpoint. :param str user: Username used to connect to server. :param str auth_token: Authentication token used to connect to server. """

        self.change_credentials(user=user, auth_token=passwd)