Firebase with esp8266

Are there any built-in functions or any libraries I can use for firebase regarding firebase database child values?

I want to use know if a new value exists in a certain child node.

Thank you

actually I search a lot in google, I won't be in here if I don't spend weeks trying to find any solutions.

You have better answer than that?

actually I used that codes, and the last one was based on the docs firebase. I think I need to import libraries in order for that to be functional. Thank you.