<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def guest_nic_couple_to_vswitch(self, userid, nic_vdev, vswitch_name, active=False):
 """ Couple nic device to specified vswitch. :param str userid: the user's name who owns the nic :param str nic_vdev: nic device number, 1- to 4- hexadecimal digits :param str vswitch_name: the name of the vswitch :param bool active: whether make the change on active guest system """

        self._networkops.couple_nic_to_vswitch(userid, nic_vdev,
                                               vswitch_name, active=active)