code: func Codec(contentType string, c encoding.Codec) server.Option {
  	return func(o *server.Options) {
  		codecs := make(map[string]encoding.Codec)
  		if o.Context == nil {
  			o.Context = context.Background()
  		}
  		if v := o.Context.Value(codecsKey{}); v != nil {
  			codecs = v.(map[string]encoding.Codec)
  		}
  		codecs[contentType] = c
  		o.Context = context.WithValue(o.Context, codecsKey{}, codecs)
  	}
  }
docs: // gRPC Codec to be used to encode/decode requests for a given content type