def _start_subprocess(self, cmd, shell=False, **env):
        """ For subclasses to easily launch the subprocess.
        """
        environ = os.environ.copy()
        environ.update(env)
        try:
            self._proc = subprocess.Popen(cmd, env=environ, shell=shell,
                                          stdout=subprocess.PIPE,
                                          stderr=subprocess.STDOUT)
        except __HOLE__ as err:  # pragma: no cover
            raise RuntimeError('Could not start runtime with command %r:\n%s' %
                               (cmd[0], str(err)))
        self._streamreader = StreamReader(self._proc)
        self._streamreader.start()
dataset/ETHPy150Open zoofIO/flexx/flexx/webruntime/common.py/BaseRuntime._start_subprocess