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: trie.go
    path of file: ./repos/corteza/server/vendor/golang.org/x/text/internal/colltab
    
    the code of the file until where you have to start completion: // Copyright 2012 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.

// The trie in this file is used to associate the first full character in an
// UTF-8 string to a collation element. All but the last byte in a UTF-8 byte
// sequence are used to lookup offsets in the index table to be used for the
// next byte. The last byte is used to index into a table of collation elements.
// For a full description, see go.text/collate/build/trie.go.

package colltab

const blockSize = 64

type Trie struct {
	Index0  []uint16 // index for first byt
    
func (t *Trie) lookupString(s string) (v Elem, sz int) {
	c0 := s[0]
	switch {
	case c0 < tx:
		return Elem(t.Values0[c0]), 1
	case c0 < t2:
		return 0, 1
	case c0 < t3:
		if len(s) < 2 {
			return 0, 0
		}
		i := t.Index0[c0]
		c1 := s[1]
		if c1 < tx || t2 <= c1 {
			return 0, 1
		}
		return t.lookupValue(i, c1), 2
	case c0 < t4:
		if len(s) < 3 {
			return 0, 0
		}
		i := t.Index0[c0]
		c1 := s[1]
		if c1 < tx || t2 <= c1 {
			return 0, 1
		}
		o := int(i)<<6 + int(c1)
		i = t.Index[o]
		c2 := s[2]
		if c2 < tx || t2 <= c2 {
			return 0, 2
		}
		return t.lookupValue(i, c2), 3
	case c0 < t5:
		if len(s) < 4 {
			return 0, 0
		}
		i := t.Index0[c0]
		c1 := s[1]
		if c1 < tx || t2 <= c1 {
			return 0, 1
		}
		o := int(i)<<6 + int(c1)
		i = t.Index[o]
		c2 := s[2]
		if c2 < tx || t2 <= c2 {
			return 0, 2
		}
		o = int(i)<<6 + int(c2)
		i = t.Index[o]
		c3 := s[3]
		if c3 < tx || t2 <= c3 {
			return 0, 3
		}
		return t.lookupValue(i, c3), 4
	}
	// Illegal rune
	return 0, 1
}