function depositCollateral(address _asset, uint256 _amount) external payable virtual {
  if (_asset != address(0)) { // asset = ERC20
    require(msg.value == 0, <AN ERROR FROM Errors LIBRARY>);
  } else { // asset = ETH
    require(msg.value == _amount, <AN ERROR FROM Errors LIBRARY>);
  }

  // Deposit asset to vault and receive stAsset
  // Ex: if user deposit 100ETH, this will deposit 100ETH to Lido and receive 100stETH TODO No Lido
  (address _stAsset, uint256 _stAssetAmount) = _depositToYieldPool(_asset, _amount);

  // Deposit stAsset to lendingPool, then user will get aToken of stAsset
  ILendingPool(_addressesProvider.getLendingPool()).deposit(
    _stAsset,
    _stAssetAmount,
    msg.sender,
    0
  );

  emit DepositCollateral(_asset, msg.sender, _amount);
}
