// Request
curl https://avalanche.blockpi.network/v1/rpc/your-rpc-key -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"eth_getBlockTransactionCountByHash","params":["0x0172873f08f73fc2395c8f79f0f0fead61fadb648f169cf40fa86e8d3b00f7e4"],"id":1}'
// Result
{
"jsonrpc": "2.0",
"id": 1,
"result": "0x2"
}