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: key.go
    path of file: ./repos/etcd/client/v3/experimental/recipes
    
    the code of the file until where you have to start completion: // Copyright 2016 The etcd Authors
//
// 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 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 recipe

    
func newSequentialKV(kv v3.KV, prefix, val string) (*RemoteKV, error) {
	resp, err := kv.Get(context.TODO(), prefix, v3.WithLastKey()...)
	if err != nil {
		return nil, err
	}

	// add 1 to last key, if any
	newSeqNum := 0
	if len(resp.Kvs) != 0 {
		fields := strings.Split(string(resp.Kvs[0].Key), "/")
		_, serr := fmt.Sscanf(fields[len(fields)-1], "%d", &newSeqNum)
		if serr != nil {
			return nil, serr
		}
		newSeqNum++
	}
	newKey := fmt.Sprintf("%s/%016d", prefix, newSeqNum)

	// base prefix key must be current (i.e., <=) with the server update;
	// the base key is important to avoid the following:
	// N1: LastKey() == 1, start txn.
	// N2: new Key 2, new Key 3, Delete Key 2
	// N1: txn succeeds allocating key 2 when it shouldn't
	baseKey := "__" + prefix

	// current revision might contain modification so +1
	cmp := v3.Compare(v3.ModRevision(baseKey), "<", resp.Header.Revision+1)
	reqPrefix := v3.OpPut(baseKey, "")
	reqnewKey := v3.OpPut(newKey, val)

	txn := kv.Txn(context.TODO())
	txnresp, err := txn.If(cmp).Then(reqPrefix, reqnewKey).Commit()
	if err != nil {
		return nil, err
	}
	if !txnresp.Succeeded {
		return newSequentialKV(kv, prefix, val)
	}
	return &RemoteKV{kv, newKey, txnresp.Header.Revision, val}, nil
}