Simple smart contract wallet

EtherWallet.sol

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;

// From Block Explorer's tutorial video: https://www.youtube.com/watch?v=UoGzV094jhE


// A smart contract acts like a wallet that can receive funds
contract EtherWallet {
    // a state variable for the owner. Only the owner will be able to withdraw funds from the wallet
    address payable public owner;

    constructor() {
        // the constructor is called 1 time: when the contract is deployed. Run any initialization code here
        owner = payable(msg.sender); // msg is a global variable. msg.sender gives us the address that is deploying this contract. By default, msg.sender is not payable so we cast it to payable

    }

    // receive ether coming in (a default function). Doesn't require the function keyword
    receive() external payable {} // invoked when ether is sent to the contract

    function withdraw(uint _amount) external {
        // put a check in place ot make sure the sender is the owner
        require(msg.sender == owner, "Only the owner can call this method");
        // transfer funds to sender
        payable(msg.sender).transfer(_amount);
    }

    // query the balance of the smart contract. External means this function can be involved by external parties. View means it is read-only
    function getBalance() external view returns (uint) {
        return address(this).balance;
    }
 }