// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_getTransactionCount","params":["0xc94770007dda54cF92009BFF0dE90c06F603a09f","latest"],"id":1}' http://klaytn.blockpi.network/v1/rpc/your-api-key
// Result
{
"jsonrpc": "2.0",
"id":1,
"result": "0x1" // 1
}