def login(self, username='<STR_LIT>', password='<STR_LIT>'):
self.session = requests.Session()<EOL>login = self.session.post(self.url+'<STR_LIT>',<EOL>data={'<STR_LIT:username>': username,<EOL>'<STR_LIT:password>': password})<EOL>if login.text == '<STR_LIT>':<EOL><INDENT>self._is_authenticated = True<EOL><DEDENT>else:<EOL><INDENT>return login.text<EOL><DEDENT>
Method to authenticate the qBittorrent Client.

Declares a class attribute named ``session`` which
stores the authenticated session if the login is correct.
Else, shows the login error.

:param username: Username.
:param password: Password.

:return: Response to login request to the API.