'configure VPN instance of the interface'

def config_interface_vrf(self):

    if ((not self.conf_exist) and (self.state == 'present')):
        xml_str = (CE_NC_MERGE_VRF_INTERFACE % (self.vrf, self.vpn_interface))
        ret_xml = set_nc_config(self.module, xml_str)
        self.check_response(ret_xml, 'VRF_INTERFACE_CONFIG')
        self.changed = True
    elif (self.state == 'absent'):
        xml_str = (CE_NC_DEL_INTF_VPN % (self.vrf, self.vpn_interface))
        ret_xml = set_nc_config(self.module, xml_str)
        self.check_response(ret_xml, 'DEL_VRF_INTERFACE_CONFIG')
        self.changed = True
