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: unicode.go
    path of file: ./repos/faygo/vendor/golang.org/x/text/encoding/unicode
    
    the code of the file until where you have to start completion: // Copyright 2013 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 unicode provides Unicode encodings such as UTF-16.
package unicode // import "golang.org/x/text/encoding/unicode"

import (
	"bytes"
	"errors"
	"unicode/utf16"
	"unicode/utf8"

	"golang.org/x/text/encoding"
	"golang.org/x/text/encoding/internal"
	"golang.org/x/text/encoding/internal/identifier"
	"golang.org/x/text/internal/utf8internal"
	"golang.org/x/text/runes"
	"golang.org/x/text/transform"
)

// TODO: I think the Transformers really should return errors on unmatched
// surrogate pairs and odd numbers of bytes. This is not required by RFC 2781,
// which leaves it open, but is suggested by WhatWG. It will allow for all error
// modes as defined by WhatWG: fatal, HTML and Replacement.
    
func (u *utf16Encoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
	if u.currentBOMPolicy&writeBOM != 0 {
		if len(dst) < 2 {
			return 0, 0, transform.ErrShortDst
		}
		dst[0], dst[1] = 0xfe, 0xff
		u.currentBOMPolicy = IgnoreBOM
		nDst = 2
	}

	r, size := rune(0), 0
	for nSrc < len(src) {
		r = rune(src[nSrc])

		// Decode a 1-byte rune.
		if r < utf8.RuneSelf {
			size = 1

		} else {
			// Decode a multi-byte rune.
			r, size = utf8.DecodeRune(src[nSrc:])
			if size == 1 {
				// All valid runes of size 1 (those below utf8.RuneSelf) were
				// handled above. We have invalid UTF-8 or we haven't seen the
				// full character yet.
				if !atEOF && !utf8.FullRune(src[nSrc:]) {
					err = transform.ErrShortSrc
					break
				}
			}
		}

		if r <= 0xffff {
			if nDst+2 > len(dst) {
				err = transform.ErrShortDst
				break
			}
			dst[nDst+0] = uint8(r >> 8)
			dst[nDst+1] = uint8(r)
			nDst += 2
		} else {
			if nDst+4 > len(dst) {
				err = transform.ErrShortDst
				break
			}
			r1, r2 := utf16.EncodeRune(r)
			dst[nDst+0] = uint8(r1 >> 8)
			dst[nDst+1] = uint8(r1)
			dst[nDst+2] = uint8(r2 >> 8)
			dst[nDst+3] = uint8(r2)
			nDst += 4
		}
		nSrc += size
	}

	if u.endianness == LittleEndian {
		for i := 0; i < nDst; i += 2 {
			dst[i], dst[i+1] = dst[i+1], dst[i]
		}
	}
	return nDst, nSrc, err
}