if (typeof id === 'object' && id.length > 0) {
                // array of dialog ids
                id.forEach(id => this.appendDialog(id));
                return;
            }

            else if (id == null) {
                this.lastDialog = null;
                // bug!!
                // this.lastDialog.responses = null;
                return;

            }

            this.isXianzheTyping = true;
            const dialog = this.getDialog(id);
            getRandomMsg(dialog.details)
                .forEach(content => {
                    this.msgChain = this.msgChain
                        .then(() => delay(700))
                        .then(() => this.sendMsg(content, AUTHOR.XIANZHE));
                });

            return dialog.nextXianzhe
                ? this.appendDialog(dialog.nextXianzhe)
                : this.msgChain.then(() => {
                    this.lastDialog = dialog;
                    this.isXianzheTyping = false;
                });
        },

        sendMsg(message, author) {
            switch (author) {
                case 'me':
                    return this.sendUserMsg(message);
                default:
                    return this.sendFriendMsg(message, author);
            }
        }, `