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: mail.go
    path of file: ./repos/bzppx-codepub/vendor/github.com/astaxie/beego/utils
    
    the code of the file until where you have to start completion: // Copyright 2014 beego Author. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package utils

import (
	"bytes"
	"encoding/base64"
	"encoding
    
func quotePrintEncode(w io.Writer, s string) error {
	var buf [3]byte
	mc := 0
	for i := 0; i < len(s); i++ {
		c := s[i]
		// We're assuming Unix style text formats as input (LF line break), and
		// quoted-printble uses CRLF line breaks. (Literal CRs will become
		// "=0D", but probably shouldn't be there to begin with!)
		if c == '\n' {
			io.WriteString(w, "\r\n")
			mc = 0
			continue
		}

		var nextOut []byte
		if isPrintable(c) {
			nextOut = append(buf[:0], c)
		} else {
			nextOut = buf[:]
			qpEscape(nextOut, c)
		}

		// Add a soft line break if the next (encoded) byte would push this line
		// to or past the limit.
		if mc+len(nextOut) >= maxLineLength {
			if _, err := io.WriteString(w, "=\r\n"); err != nil {
				return err
			}
			mc = 0
		}

		if _, err := w.Write(nextOut); err != nil {
			return err
		}
		mc += len(nextOut)
	}
	// No trailing end-of-line?? Soft line break, then. TODO: is this sane?
	if mc > 0 {
		io.WriteString(w, "=\r\n")
	}
	return nil
}