如何验证智能合约中收到的代币的类型/名称？

如何解决如何验证智能合约中收到的代币的类型/名称？

这是一份示例合同，旨在收取xyz token。合同如何验证发送的是xyz token？

pragma "^0.7.0"

contract myContract {
  address public payable owner;
  uint public value;  //<<==xyz token

  constructor(uint _value) payable {
    owner = msg.sender;
    value = _value;  //<<== how does the contract verify it is the _value of xyz token?
  }
}