CODE EXAMPLE FOR SHELL

ico buy function

     function buy ()   payable external    returns (bool){
         uint amounttoBuy =(msg.value*tokenQuantity)/1 ether;
         require(amounttoBuy<token.allowance(tokenOwner,address(this)),"Not Alloted Token to this Address");
         token.transferFrom(tokenOwner,msg.sender,amounttoBuy);
         return true;
     }