def os_change(self, subid, osid, params=None):
        ''' /v1/server/os_change
        POST - account
        Changes the operating system of a virtual machine. All data will be
        permanently lost.

        Link: https://www.vultr.com/api/#server_os_change
        '''
        params = update_params(params, {
            'SUBID': subid,
            'OSID': osid
        })
        return self.request('/v1/server/os_change', params, 'POST')
/v1/server/os_change
        POST - account
        Changes the operating system of a virtual machine. All data will be
        permanently lost.

        Link: https://www.vultr.com/api/#server_os_change