Initialises the OAuth2 Process by asking the auth server for a login URL.
            Once called, the user can login by being redirected to the url returned by
            this function.
            If there is an error during authorisation, None is returned.

def get_authorisation_url(self, reset=False):
        """ Initialises the OAuth2 Process by asking the auth server for a login URL.
            Once called, the user can login by being redirected to the url returned by
            this function.
            If there is an error during authorisation, None is returned."""

        if reset:
            self.auth_url = None
        if not self.auth_url:
            try:
                oauth = OAuth2Session(self.client_id,redirect_uri=self.redirect_url)
                self.auth_url,self.state = oauth.authorization_url(self.auth_base_url)
            except Exception:
                #print("Unexpected error:", sys.exc_info()[0])
                #print("Could not get Authorisation Url!")
                return None

        return self.auth_url