<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(self, value):
        '''
        set the value for user in gsettings

        '''
        user = self.USER
        try:
            uid = pwd.getpwnam(user).pw_uid
        except KeyError:
            log.info('User does not exist')
            result = {}
            result['retcode'] = 1
            result['stdout'] = 'User {0} does not exist'.format(user)
            return result

        cmd = self.gsetting_command + ['set', self.SCHEMA, self.KEY, value]
        environ = {}
        environ['XDG_RUNTIME_DIR'] = '/run/user/{0}'.format(uid)
        result = __salt__['cmd.run_all'](cmd, runas=user, env=environ, python_shell=False)
        return result