干布球和tt 的提示，解决了报错。
import websocket #pip install websocket-client
import _thread as thread

在查找资料时，看到了：
import websocket
try:
    import thread
except ImportError:
    import _thread as thread

尝试回答下Destroy的问题：
查看WebsocketApp函数：
on_message: callable object which is called when received data.
 on_message has 2 arguments.
 The 1st argument is this class object.
 The 2nd argument is utf-8 string which we get from the server.
你如果直接on_message = self.on_message，那么会缺少第一个参数，因为class Crawler类里on_message(self,message)是缺少如最上面老师例子def on_message(ws, message)里的ws的。所以
on_message = lambda ws, message: self.on_message(message)是通过lambda补上第一个参数ws。

请问老师，下面代码中select.select是什么意思，这段代码主要起到什么作用
class Dispatcher:
    def __init__(self, app, ping_timeout):
        self.app = app
        self.ping_timeout = ping_timeout

    def read(self, sock, read_callback, check_callback):
        while self.app.sock.connected:
            r, w, e = select.select(
                    (self.app.sock.sock, ), (), (), self.ping_timeout)
            if r:
                if not read_callback():
                    break
            check_callback()