This is for the tutorial that teaches about the MSG object

MsgObject.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract TransactionInfo {
    address public owner;
    uint256 public contractBalance;

    constructor() {
        // Set the owner to the account that deploys the contract
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(msg.sender == owner, "Only the owner can call this function");
        _;
    }

    function sendEther() external payable {
        // Receive Ether and update contract balance
        contractBalance += msg.value;
    }

    function getSender() external view returns (address) {
        // Get the sender's address
        return msg.sender;
    }

    function getValueSent() external view returns (uint256) {
        // Get the amount of Ether sent with the transaction
        return msg.value;
    }

    function getData() external view returns (bytes memory) {
        // Get the data payload of the transaction
        return msg.data;
    }

    function getGasRemaining() external view returns (uint256) {
        // Get the remaining gas for the current execution
        return gasleft();
    }

    function getFunctionSignature() external pure returns (bytes4) {
        // Get the function signature of the function being called
        return msg.sig;
    }

    function withdraw() external onlyOwner {
        // Only the owner can withdraw the contract balance
        uint256 amount = contractBalance;
        contractBalance = 0;
        payable(owner).transfer(amount);
    }
}


// Here's a brief explanation of the functions:

// - `sendEther`: Allows anyone to send Ether to the contract, updating the contract balance.
// - `getSender`: Returns the address of the sender of the transaction.
// - `getValueSent`: Returns the amount of Ether sent with the transaction.
// - `getData`: Returns the data payload of the transaction.
// - `getGasRemaining`: Returns the remaining gas for the current execution.
// - `getFunctionSignature`: Returns the function signature of the function being called.
// - `withdraw`: Only the owner can withdraw the contract balance.

// Please note that this is a simple example for educational purposes, and in a production scenario, additional security measures and considerations should be taken into account.