Solidity

pragma solidity >=0.5.0 <0.7.0;
contract Coin {
    // The keyword "public" makes variables
    // accessible from other contracts
    address public minter;
    mapping (address => uint) public balances;
    mapping (address => mapping (address => uint256)) public allowed;
    // Events allow clients to react to specific
    // contract changes you declare
    event Transfer (address from, address to, uint amount);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
    event MintingRightTransferred(address indexed oldMinter, address indexed newMinter);
    string public symbol = "WIKI";
    string public name = "WikiArticleToken";
    uint256 public totalSupply;
    // Constructor code is only run when the contract
    // is created
    constructor() public {
        minter = msg.sender;
    }
    // Sends an amount of newly created coins to an address
    // Can only be called by the contract creator
    function mint(address receiver, uint amount) public {
        require(msg.sender == minter);
        require(amount <= 2**256-1); // be aware of high amounts since overflow exist
        balances[receiver] += amount;
        totalSupply += amount;
        emit Transfer(address(0), receiver, amount);
    }
    // Sends an amount of existing coins
    // from any caller to an address
    function transfer(address receiver, uint amount) public {
        require(amount <= balances[msg.sender], "Insufficient balance.");
        balances[msg.sender] -= amount;
        balances[receiver] += amount;
        emit Transfer(msg.sender, receiver, amount);
    }
    function transferFrom(address from, address to, uint256 amount) public returns (bool success) {
        require((allowed[from][msg.sender]||(from == msg.sender)) >= amount, "You aren't allowed to spend this amount");
        require(amount <= balances[from], "Insufficient balance");
        allowed[from][msg.sender] -= amount;
        balances[from] -= amount;
        balances[to] += amount;
        emit Transfer(from, to, amount);
        return true;
    }
    function allowance(address tokenOwner, address spender) public view returns (uint remaining) {
		return allowed[tokenOwner][spender];
    }
    function approve(address spender, uint tokens) public returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        return true;
    }
    function balanceOf(address guy) public view returns (uint256 balance) {
        return balances[guy];
    }
    function transferMinterRight(address _newMinter) public {
        require(msg.sender == minter);
        emit MintingRightTransferred(minter, _newMinter);
        minter = _newMinter;
    }
}