code: func SetEncoder(encoding string, fn EncoderFunc) {
  	if defaultCompressor == nil {
  		panic("no compressor to set encoders on. Call Compress() first")
  	}
  	defaultCompressor.SetEncoder(encoding, fn)
  }
docs: // SetEncoder can be used to set the implementation of a compression algorithm.
  //
  // The encoding should be a standardised identifier. See:
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding
  //
  // For example, add the Brotli algortithm:
  //
  //  import brotli_enc "gopkg.in/kothar/brotli-go.v0/enc"
  //
  //  middleware.SetEncoder("br", func(w http.ResponseWriter, level int) io.Writer {
  //    params := brotli_enc.NewBrotliParams()
  //    params.SetQuality(level)
  //    return brotli_enc.NewBrotliWriter(params, w)
  //  })
  //
  //  DEPRECATED