function getCurrentPrice(
    uint256 _stockId,
    uint256 _shareId
  ) public view returns (uint256 currentPrice) {
    require(_stockId < stocks.length && _shareId < shares.length);
    currentPrice = SafeMath.div(
      SafeMath.mul(stocks[_stockId].priceIncrease, shares[_shareId].purchasePrice),
      100
    );
  }