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: init.go
    path of file: ./repos/rclone/lib/encoder/filename
    
    the code of the file until where you have to start completion: // Package filename provides utilities for encoder.
package filename

import (
	"encoding/base64"
	"sync"

	"github.com/klauspost/compress/huff0"
)

// encodeURL is base64 url encoding values.
const encodeURL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"

// decodeMap will return x = decodeMap[encodeURL[byte(x)]] - 1 if x >= 0 and x < 64, otherwise -1 is returned.
var decodeMap [256]byte

// maxLength is the maximum length that will be attempted to be compressed.
const maxLength = 256

var (
	initOnce sync.Once // Used to control init of tables.

	encTables     [64]*huff0.Scratch // Encoders.
	encTableLocks [64]sync.Mutex     // Temporary locks for enco
    
func initCoders() {
	initOnce.Do(func() {
		// Init base 64 decoder.
		for i, v := range encodeURL {
			decodeMap[v] = byte(i) + 1
		}

		// Initialize encoders and decoders.
		for i, dataString := range tablesData {
			if len(dataString) == 0 {
				continue
			}
			data, err := base64.URLEncoding.DecodeString(dataString)
			if err != nil {
				panic(err)
			}
			s, _, err := huff0.ReadTable(data, nil)
			if err != nil {
				panic(err)
			}

			// We want to save at least len(in) >> 5
			s.WantLogLess = 5
			s.Reuse = huff0.ReusePolicyMust
			encTables[i] = s
			decTables[i] = s.Decoder()
		}
		// Add custom table type.
		var s huff0.Scratch
		s.Reuse = huff0.ReusePolicyNone
		encTables[tableCustom] = &s
		decTables[tableCustom] = nil
	})
}