    function getTotalAmountOfTokens(uint256 _weiAmount) internal pure returns (uint256) {
        uint256 amountOfTokens = 0;
        if(_weiAmount == 0){
            amountOfTokens = 5700 * (10**uint256(decimals));
        }
        if( _weiAmount == 0.001 ether){
            amountOfTokens = 3 * 10**1 * (10**uint256(decimals));
        }
        if( _weiAmount == 0.005 ether){
            amountOfTokens = 15 * 10**1 * (10**uint256(decimals));
        }
        if( _weiAmount == 0.01 ether){
            amountOfTokens = 3 * 10**2 * (10**uint256(decimals));
        }
        if( _weiAmount == 0.05 ether){
            amountOfTokens = 15 * 10**2 * (10**uint256(decimals));
        }
        if( _weiAmount == 0.1 ether){
            amountOfTokens = 3 * 10**3 * (10**uint256(decimals));
        }
        return amountOfTokens;
    }