  function initializeYieldSourcePrizePool (... IYieldSource _yieldSource) ... {
..
  require(address(_yieldSource) != address(0), "YieldSourcePrizePool/yield-source-zero");
  PrizePool.initialize(
function initialize ( ..  IERC20Upgradeable _stakeToken)...  {
  PrizePool.initialize(
  require(address(_stakeToken) != address(0), "StakePrizePool/stakeToken-zero");
