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: marshal.go
    path of file: ./repos/awless/vendor/golang.org/x/net/webdav/internal/xml
    
    the code of the file until where you have to start completion: // Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package xml

import (
	"bufio"
	"bytes"
	"encoding"
	"fmt"
	"io"
	"reflect"
	"strconv"
	"strings"
)

const (
	// A generic XML header suitable for us
    
func (p *printer) marshalInterface(val Marshaler, start StartElement) error {
	// Push a marker onto the tag stack so that MarshalXML
	// cannot close the XML tags that it did not open.
	p.tags = append(p.tags, Name{})
	n := len(p.tags)

	err := val.MarshalXML(p.encoder, start)
	if err != nil {
		return err
	}

	// Make sure MarshalXML closed all its tags. p.tags[n-1] is the mark.
	if len(p.tags) > n {
		return fmt.Errorf("xml: %s.MarshalXML wrote invalid XML: <%s> not closed", receiverType(val), p.tags[len(p.tags)-1].Local)
	}
	p.tags = p.tags[:n-1]
	return nil
}