docs: def start(self):
          """ Start Crossbar.io in a subprocess.
          """
          if self.started is True:
              raise WampyError("Router already started")
  
          # will attempt to connect or start up the CrossBar
          crossbar_config_path = self.config_path
          cbdir = self.crossbar_directory
  
          # starts the process from the root of the test namespace
          cmd = [
              'crossbar', 'start',
              '--cbdir', cbdir,
              '--config', crossbar_config_path,
          ]
  
          self.proc = subprocess.Popen(cmd, preexec_fn=os.setsid)
  
          self._wait_until_ready()
          logger.info(
              "Crosbar.io is ready for connections on %s (IPV%s)",
              self.url, self.ipv
          )
  
          self.started = True