function sell(uint256 amount) public {
        bool sendSUCCESS = false;
        if (balanceOf[msg.sender] < amount ) revert();        
        balanceOf[this] += amount;                         
        balanceOf[msg.sender] -= amount;                   
        
        
        sendSUCCESS = msg.sender.send(amount * sellPrice);
        if (!sendSUCCESS) {                                     
            revert();                                           
        } else {
            Transfer(msg.sender, this, amount);                 
        }               
    }