code: def password_credentials(self, username, password, **kwargs):
          
          return self._token_request(grant_type='password',
                                     username=username, password=password,
                                     **kwargs)
docs: Retrieve access token by 'password credentials' grant.
  
          https://tools.ietf.org/html/rfc6749#section-4.3
  
          :param str username: The user name to obtain an access token for
          :param str password: The user's password
          :rtype: dict
          :return: Access token response