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: texttree.go
    path of file: ./repos/tidb/pkg/util/texttree
    
    the code of the file until where you have to start completion: // Copyright 2019 PingCAP, Inc.
//
// 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 ap
    
func Indent4Child(indent string, isLastChild bool) string {
	if !isLastChild {
		return string(append([]rune(indent), TreeBody, TreeGap))
	}

	// If the current node is the last node of the current operator tree, we
	// need to end this sub-tree by changing the closest treeBody to a treeGap.
	indentBytes := []rune(indent)
	for i := len(indentBytes) - 1; i >= 0; i-- {
		if indentBytes[i] == TreeBody {
			indentBytes[i] = TreeGap
			break
		}
	}

	return string(append(indentBytes, TreeBody, TreeGap))
}