Listen to swaps between two tokens on Balancer

Unit1.pas

const client: IWeb3 = TWeb3.Create(
  web3.eth.infura.endpoint(web3.Ethereum, INFURA_PROJECT_ID).Value
);

const task = web3.eth.balancer.v2.listen(
  client,
  procedure(
    blockNo  : BigInteger;
    poolId   : TBytes32;
    tokenIn  : TAddress;
    tokenOut : TAddress;
    amountIn : BigInteger;
    amountOut: BigInteger)
  begin
    // a swap between two tokens happened 
  end);

task.Start;