How to add my own DecoderInterface?

[Spider84]

Hello! I want to implement my DecoderInterface but I don't know how to "connect" my class to Rest. As I understand I must define my decoder in config.yml:

fos_rest:
    body_listener:
        enabled: true
        decoders:
            mango: decoder_mango

But where definition of decoder_mango class? How? Help, pls.

[xabbuh]

decoder_mango must be the name of your custom service that implements the DecoderInterface.