How to use the mediacloud.error.MCException function in mediacloud

headers={'Accept': 'application/json', 'Content-Type': 'application/json'})
            except Exception as e:
                logger.error(u'Failed to POST {} because {}'.format(url, e))
                raise e
        else:
            raise ValueError('Error - unsupported HTTP method {}'.format(http_method))
        end_time = time.time()
        logger.debug(u"Profiling: {}s for {} to {} (with {} / {})".format(end_time - start_time, http_method,
                                                                          url, params,
                                                                          json.dumps(_remove_private_info(json_data))))
        if r.status_code is not requests.codes['ok']:
            logger.info(u'Bad HTTP response to {}: {} {}'.format(r.url, r.status_code, r.reason))
            # logger.info(u'\t{}'.format(r.content))
            msg = u'Error - got a HTTP status code of {} with the message "{}", body: {}'.format(r.status_code,
                                                                                                 r.reason, r.text)
            raise mediacloud.error.MCException(msg, r.status_code)
        return r

user_mc = user_admin_mediacloud_client()
    new_permissions = json.loads(request.form["permissions"])
    current_permissions = user_mc.topicPermissionsList(topics_id)['permissions']
    # first remove any people that you need to
    new_emails = [p['email'] for p in new_permissions]
    current_emails = [p['email'] for p in current_permissions]
    for email in current_emails:
        if email not in new_emails:
            user_mc.topicPermissionsUpdate(topics_id, email, 'none')
    # now update the remaining permissions
    for permission in new_permissions:
        if permission['permission'] not in ['read', 'write', 'admin', 'none']:
            return json_error_response('Invalid permission value')
        try:
            user_mc.topicPermissionsUpdate(topics_id, permission['email'], permission['permission'])
        except MCException as e:
            # show a nice error if they type the email wrong
            if 'Unknown email' in e.message:
                return jsonify({'success': 0, 'results': e.message})
    return jsonify({'success': 1, 'results': user_mc.topicPermissionsList(topics_id)})

def activation_confirm():
    logger.debug("activation request from %s", request.args['email'])
    try:
        results = mc.authActivate(request.args['email'], request.args['activation_token'])
        if results['success'] is 1:
            redirect_to_return = redirect(AUTH_MANAGEMENT_DOMAIN + '/#/user/activated?success=1')
        else:
            redirect_to_return = redirect(AUTH_MANAGEMENT_DOMAIN + '/#/user/activated?success=0&msg=' +
                                          results['error'])
    except MCException as mce:
        # this is long stack trace so we have to trim it for url length support
        redirect_to_return = redirect(AUTH_MANAGEMENT_DOMAIN + '/#/user/activated?success=0&msg=' + str(mce[:300]))
    return redirect_to_return

def _queryForJson(self, url, params=None, http_method='GET', json_data=None):
        # Helper that returns queries to the API as real objects
        response = self._query(url, params, http_method, json_data)
        # print response.content
        response_json = response.json()
        # print json.dumps(response_json, indent=2)
        if 'error' in response_json:
            logger.error(u'Error in response from server on request to {}: {}'.format(url, response_json['error']))
            raise mediacloud.error.MCException(response_json['error'], requests.codes['ok'])
        return response_json