You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: minify.go
    path of file: ./repos/gotosocial/vendor/github.com/tdewolff/minify/v2
    
    the code of the file until where you have to start completion: // Package minify relates MIME type to minifiers. Several minifiers are provided in the subpackages.
package minify

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"mime"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"path"
	"regexp"
	"strings"
	"sync"

	"github.com/tdewolff/parse/v2"
	"github.com/tdewolff/parse/v2/buffer"
)

// Warning is used to report usage warnings such as using a deprecated feature
var Warning = log.New(os.Stderr, "WARNING: ", 0)

// ErrNotExist is returned when no minifie
    
func (w *responseWriter) Write(b []byte) (int, error) {
	if w.z == nil {
		// first write
		if mediatype := w.ResponseWriter.Header().Get("Content-Type"); mediatype != "" {
			w.mediatype = mediatype
		}
		if _, params, minifier := w.m.Match(w.mediatype); minifier != nil {
			pr, pw := io.Pipe()
			z := &writer{pw, sync.WaitGroup{}, false, nil}
			z.wg.Add(1)
			go func() {
				defer z.wg.Done()
				defer pr.Close()
				if err := minifier(w.m, w.ResponseWriter, pr, params); err != nil {
					z.err = err
				}
			}()
			w.z = z
		} else {
			w.z = w.ResponseWriter
		}
	}
	return w.z.Write(b)
}