animabank.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

contract AnimaBank {

    //Properties
    address public owner;
    mapping (address => uint) private balances;

    //Events
    event OwnerChanged(address oldOwner, address newOwner);
    event BalanceIncreased(address to, uint amount);

    //Modifiers
    modifier isOwner() {
        require(msg.sender == owner , "Sender is not owner!");
        _;
    }

    //Constructor
    constructor() {
        // MSG.SENDER é o responsavel pela transação
        owner = msg.sender; // 0xabc123f....BC
    }

    //Public functions
    function addBalance(address to, uint amount) public isOwner {
        balances[to] += amount;
        emit BalanceIncreased(to, amount);
    }

    function getBalance() public view returns (uint) {
        return balances[msg.sender];
    }

    function changeOwner(address newOwnerAnimaBank) public isOwner {
        emit OwnerChanged(owner, newOwnerAnimaBank);
        owner = newOwnerAnimaBank;
        
    }

}

animatoken.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

contract AnimaToken {

    //Properties
    string public constant name = "AnimaToken";
    string public constant symbol = "ANT";
    uint8 public constant decimals = 18;
    uint256 private totalsupply;

    mapping(address => uint256) private balances;

    //Events
    event Transfer(address from, address to, uint256 value);

    //Constructor
    constructor(uint256 initialSupply) {
        totalsupply = initialSupply;
        balances[msg.sender] = totalsupply;
    }

    //Public Functions
    function totalSupply() public view returns (uint256) {
        return totalsupply;
    }

    function balanceOf(address tokenOwner) public view returns(uint256) {
        return balances[tokenOwner];
    }

    function transfer(address receiver, uint256 amount) public returns (bool) {
        require(amount <= balances[msg.sender], "Insufficient Balance to Transfer");
        balances[msg.sender] -= amount; // balances[msg.sender] = balances[msg.sender] - amount
        balances[receiver] += amount;

        emit Transfer(msg.sender, receiver, amount);
        return true;
    }

}

storage.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

contract Storage {

    // Properties
    int private numeroArmazenado;

    //Constructor
    constructor() { }

    // Public Functions
    function get() public view returns (int){
        return numeroArmazenado;
    }

    function store(int n) public {
        numeroArmazenado = n;
    }

}