contract Context {
    /**
     * @return Address of the transaction message sender {msg.sender}
     * Returns the msg.sender
     */
    function _msgSender() internal view returns (address) {
        return msg.sender;
    }
}
function _msgSender() internal view returns (address) {
    return msg.sender;
}

/**
 * @return Address of the transaction message sender {msg.sender}
 * Returns the msg.sender
 */