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: xform.go
    path of file: ./repos/protobuf-go/testing/protocmp
    
    the code of the file until where you have to start completion: // Copyright 2019 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 protocmp provides protobuf specific options for the
// [github.com/google/go-cmp/cmp] package.
//
// The primary feature is the [Transform] option, which transform [proto.Message]
// types into a [Message] map that is suitable for cmp to introspect upon.
// All other options in this package must be used in conjunction with [Transform].
package protocmp

import (
	"reflect"
	"strconv"

	"github.com/google/go-cmp/cmp"

	"google.golang.org/protobuf/encoding/protowire"
	"google.golang.org/protobuf/internal/genid"
	"google.golang.org/protobuf/internal/msgfmt"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/reflect/protoreflect"
	"google.golang.org/protobuf/reflect/protoregistry"
	"google.golang.org/protobuf/runtime/protoiface"
	"google.golang.org/protobuf/runtime/protoimpl"
)

var (
	enumV2Type    = reflect.TypeOf((*protoreflect.Enum)(nil)).Elem()
	messageV1Type = reflect.TypeOf((*protoiface.MessageV1)(nil)).Elem()
	messageV2Type = reflect.TypeOf((*proto.Message)(nil)).Elem()
)

// Enum is a dynamic representation of a protocol buffer enum that is
// suitable for [cmp.Equal] and [cmp.Diff] to 
    
func Transform(opts ...option) cmp.Option {
	xf := newTransformer(opts...)

	// addrType returns a pointer to t if t isn't a pointer or interface.
	addrType := func(t reflect.Type) reflect.Type {
		if k := t.Kind(); k == reflect.Interface || k == reflect.Ptr {
			return t
		}
		return reflect.PtrTo(t)
	}

	// TODO: Should this transform protoreflect.Enum types to Enum as well?
	return cmp.FilterPath(func(p cmp.Path) bool {
		ps := p.Last()
		if isMessageType(addrType(ps.Type())) {
			return true
		}

		// Check whether the concrete values of an interface both satisfy
		// the Message interface.
		if ps.Type().Kind() == reflect.Interface {
			vx, vy := ps.Values()
			if !vx.IsValid() || vx.IsNil() || !vy.IsValid() || vy.IsNil() {
				return false
			}
			return isMessageType(addrType(vx.Elem().Type())) && isMessageType(addrType(vy.Elem().Type()))
		}

		return false
	}, cmp.Transformer("protocmp.Transform", func(v interface{}) Message {
		// For user convenience, shallow copy the message value if necessary
		// in order for it to implement the message interface.
		if rv := reflect.ValueOf(v); rv.IsValid() && rv.Kind() != reflect.Ptr && !isMessageType(rv.Type()) {
			pv := reflect.New(rv.Type())
			pv.Elem().Set(rv)
			v = pv.Interface()
		}

		m := protoimpl.X.MessageOf(v)
		switch {
		case m == nil:
			return nil
		case !m.IsValid():
			return Message{messageTypeKey: messageMeta{m: m.Interface(), md: m.Descriptor()}, messageInvalidKey: true}
		default:
			return xf.transformMessage(m)
		}
	}))
}