code: func (m Client) Transformer(mediatype media.Type) transform.Transformer {
  	_, params, min := m.m.Match(mediatype.Type())
  	if min == nil {
  		// No minifier for this MIME type
  		return nil
  	}
  
  	return func(ft transform.FromTo) error {
  		// Note that the source io.Reader will already be buffered, but it implements
  		// the Bytes() method, which is recognized by the Minify library.
  		return min.Minify(m.m, ft.To(), ft.From(), params)
  	}
  }
docs: // Transformer returns a func that can be used in the transformer publishing chain.
  // TODO(bep) minify config etc