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: cursor.go
    path of file: ./repos/bk-cmdb/src/common/watch
    
    the code of the file until where you have to start completion: /*
 * Tencent is pleased to support the open source community by making 蓝鲸 available.
 * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
 * Licensed under the MIT License (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * http://opensource.org/licenses/MIT
 * Unless required by applicable law or agreed to in writing, software distributed under
 * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */

package watch

import (
	"bytes"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"strconv"

	"configcenter/src/common"
	"configcenter/src/common/blog"
	kubetypes "configcenter/src/kube/types"
	"configcenter/src/storage/stream/types"

	"github.com/tidwall/
    
func GetEventCursor(coll string, e *types.Event, instID int64) (string, error) {
	curType, exists := collEventCursorTypeMap[coll]
	if !exists {
		blog.Errorf("unsupported cursor type collection: %s, oid: %s", e.ID())
		return "", fmt.Errorf("unsupported cursor type collection: %s", coll)
	}

	hCursor := &Cursor{
		Type:        curType,
		ClusterTime: e.ClusterTime,
		Oid:         e.Oid,
		Oper:        e.OperationType,
	}

	switch curType {
	case ObjectBase, MainlineInstance, InstAsst:
		if instID <= 0 {
			return "", errors.New("invalid instance id")
		}

		// add unique key for common object instance.
		hCursor.UniqKey = strconv.FormatInt(instID, 10)
	case KubeWorkload:
		if instID <= 0 {
			return "", errors.New("invalid kube workload id")
		}

		// add unique key for kube workload, composed by workload type and id.
		hCursor.UniqKey = fmt.Sprintf("%s:%d", gjson.GetBytes(e.DocBytes, kubetypes.KindField).String(), instID)
	}

	hCursorEncode, err := hCursor.Encode()
	if err != nil {
		blog.Errorf("encode node cursor failed, err: %v, oid: %s", err, e.Oid)
		return "", err
	}

	return hCursorEncode, nil
}