code: def _post_login_page(self, login_url):
          
          data = {"login": self.username,
                  "_58_password": self.password}
  
          try:
              raw_res = yield from self._session.post(login_url,
                                                      data=data,
                                                      timeout=self._timeout,
                                                      allow_redirects=False)
          except OSError:
              raise PyHydroQuebecError("Can not submit login form")
          if raw_res.status != 302:
              raise PyHydroQuebecError("Login error: Bad HTTP status code. "
                                       "Please check your username/password.")
          return True
docs: Login to HydroQuebec website.