How to subscribe to pending transaction in Ethereum?

Question

I'm trying to subscribe to pending transaction in Ethereum. Whilest I know how to do in web3.js

const subscription = web3.eth.subscribe("pendingTransactions", (err, res) => {
  if (err) console.error(err);
});

I haven't been able to find any method to do in Go. For instance, this method doesn't exist:

  import (
    "context"
    "fmt"
    "log"

    "github.com/ethereum/go-ethereum"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/ethclient"
   )

    //........
    client, err := ethclient.Dial("<URL>")
    gethClient := gethclient.New(rpcClient)


    //.....
    logs := make(chan types.Log)
    sub, err := gethClient.SubscribePendingTransactions(context.Background(), logs) // doesn't exit

client.SubscribePendingTransactions undefined (type *ethclient.Client has no field or method SubscribePendingTransactions)

What's the method for that?