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: element_uml_generator.go
    path of file: ./repos/cockroach/pkg/sql/schemachanger/scpb
    
    the code of the file until where you have to start completion: // Copyright 2021 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.

//go:build generator
// +build generator

package main

import (
	"bytes"
	"flag"
	"fmt"
	"os"
	"reflect"
	"strings"

	"github.com/cockroachdb/cockroach/pkg/cli/exit"
	"github.com/cockroachdb/cockroach/pkg/sql/schemachanger/scpb"
)

var (
	out = flag.String("out", "", "output file for generated UML")
)

func main() {
	flag.Parse()
	if err := run(*out); err != nil {
		fmt.Fprintf(os.Stderr, "%v\n", err)
		exit.WithCode(exit.FatalError())
	}
}
func run(out string) error {
	if out == "" {
		return fmt.Errorf("output required")
	}
	var buf bytes.Buffer
	var parentRelations bytes.Buffer

	getParentsFromField := func(f reflect.StructField) []string {
		if parentTag := f.Tag.Get("parent"); parentTag != "" {
			return strings.Split(parentTag, ", ")
		}
		return nil
	}

	buf.WriteString("@startuml\n")
	elementProtoType := reflect.TypeOf((*scpb.ElementProto)(nil))
	for i := 0; i <
    
func run(out string) error {
	if out == "" {
		return fmt.Errorf("output required")
	}
	var buf bytes.Buffer
	var parentRelations bytes.Buffer

	getParentsFromField := func(f reflect.StructField) []string {
		if parentTag := f.Tag.Get("parent"); parentTag != "" {
			return strings.Split(parentTag, ", ")
		}
		return nil
	}

	buf.WriteString("@startuml\n")
	elementProtoType := reflect.TypeOf((*scpb.ElementProto)(nil))
	for i := 0; i < elementProtoType.NumMethod(); i++ {
		if !strings.HasPrefix(elementProtoType.Method(i).Name, "Get") ||
			elementProtoType.Method(i).Name == "GetElementOneOf" {
			continue
		}
		fieldType := elementProtoType.Method(i).Type.Out(0).Elem()
		buf.WriteString(fmt.Sprintf(
			"object %s\n\n",
			fieldType.Name()))
		for j := 0; j < fieldType.NumField(); j++ {
			arrayPrefix := " "
			if fieldType.Field(j).Type.Kind() == reflect.Slice {
				arrayPrefix = "[]"
			}
			buf.WriteString(
				fmt.Sprintf("%s : %s%s\n",
					fieldType.Name(),
					arrayPrefix,
					fieldType.Field(j).Name),
			)
		}
		buf.WriteString("\n")
		// The parent tag has a list of elements that are the parents
		// to this element. We will collect these and emit them later
		// in the PlantUML syntax.
		oneOfTypes := scpb.GetElementOneOfProtos()
		typeProto := reflect.TypeOf(scpb.GetElementOneOfProtos()[0]).Elem()
		for _, oneOf := range oneOfTypes {
			oneOfType := reflect.TypeOf(oneOf).Elem()
			if oneOfType.Field(0).Type.Elem() == fieldType {
				typeProto = oneOfType
			}
		}
		for _, parent := range getParentsFromField(typeProto.Field(0)) {
			parentRelations.WriteString(fmt.Sprintf(
				"%s <|-- %s\n", parent, fieldType.Name()))
		}
	}
	// Append all the object relationships at
	// the end.
	buf.Write(parentRelations.Bytes())
	buf.WriteString("@enduml\n")
	return os.WriteFile(out, buf.Bytes(), 0777)
}