code: func (h *Handler) siteSessionsGet(w http.ResponseWriter, r *http.Request, p httprouter.Params, ctx *SessionContext, site reversetunnel.RemoteSite) (interface{}, error) {
  	clt, err := ctx.GetUserClient(site)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  
  	namespace := p.ByName("namespace")
  	if !services.IsValidNamespace(namespace) {
  		return nil, trace.BadParameter("invalid namespace %q", namespace)
  	}
  
  	sessions, err := clt.GetSessions(namespace)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	return siteSessionsGetResponse{Sessions: sessions}, nil
  }
docs: // siteSessionGet gets the list of site sessions filtered by creation time
  // and either they're active or not
  //
  // GET /v1/webapi/sites/:site/namespaces/:namespace/sessions
  //
  // Response body:
  //
  // {"sessions": [{"id": "sid", "terminal_params": {"w": 100, "h": 100}, "parties": [], "login": "bob"}, ...] }