The value for the "isconfigured" key returned as part of the learn("ntp") dict differs in that it is a string for NXOS and a boolean value for IOS/IOS-XE.
NXOS
"VRF1": {
"associations": {
"address": {
"10.64.4.4": {
"local_mode": {
"client": {
"isconfigured": {
"True": {
IOS-XE
'vrf': {
'default': {
'associations': {
'address': {
'127.127.1.1': {
'local_mode': {
'client': {
'isconfigured': {
False: {