<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def set_host(self, host):
 """ Set the host for a lightning server. Host can be local (e.g. http://localhost:3000), a heroku instance (e.g. http://lightning-test.herokuapp.com), or a independently hosted lightning server. """

        if host[-1] == '/':
            host = host[:-1]

        self.host = host
        return self