Why is the output null? Is it the error in code?

Question

https://code.sololearn.com/WcTJl81K1pSK/?ref=app
Here is the code please correct it or give me it's info

Answer 1

Bibek This is the problem of your API. You need to check that. We cannot help because we don't know what you have written in that API.

Answer 2

It's fixed