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contracts...SimpleCoin.sol

pragma solidity ^0.4.0;

contract SimpleCoin {
    mapping (address => uint256) public coinBalance;
    // Allowance is used to limit the number of coins an address can 
    // use in transferFrom
    mapping (address => mapping (address => uint256)) public allowance;
    mapping (address => bool) public frozenAccount;
    address public owner;
    
    // Events are used to notify other clients / contracts about things that happen
    // Define the transfer event.
    event Transfer(address indexed from, address indexed to, uint256 value);
    //Define freeze event for account
    event FrozenAccount(address target, bool frozen);
    
    // Modifiers are used to dry out checks for functions
    modifier onlyOwner {
        if (msg.sender != owner) revert();
        _;
    }
    
    // Define the owner on contract creation
    constructor(uint256 _initialSupply) public {
        owner = msg.sender;
        mint(owner, _initialSupply);
    }
    
    function transfer(address _to, uint256 _amount) public {
        require(_to != 0x0);
        require(coinBalance[msg.sender] >= _amount);
        require((coinBalance[_to] += _amount) >= coinBalance[_to]);
        coinBalance[msg.sender] -= _amount;
        coinBalance[_to] += _amount;
        
        // Publish Transfer event
        emit Transfer(msg.sender, _to, _amount);
    }
    
    function authorize(address _authorizedAccount, uint256 _allowance) public returns (bool success){
        allowance[msg.sender][_authorizedAccount] = _allowance;
        return true;
    }
    
    // Check the balances and the allowance to make sure that the address can transferFrom
    // the amount. Emit transfer and success 
    function transferFrom(address _from, address _to, uint256 _amount) public returns (bool success){
        require(_to != 0x0);
        require(coinBalance[_from] >= _amount);
        require((coinBalance[_to] += _amount) >= coinBalance[_to]);
        require(_amount <= allowance[_from][msg.sender]);
        
        coinBalance[_from] -= _amount;
        coinBalance[_to] += _amount;
        allowance[_from][msg.sender] -= _amount;
        // Publish transfer event
        emit Transfer(_from, _to, _amount);
        return true;
    }
    
    // Creating coins is limited to the owner and considered a transfer even though 
    // the coins are 'created'
    function mint(address _recipient, uint256 _mintedAmount) onlyOwner public {
            coinBalance[_recipient] += _mintedAmount;
            emit Transfer(owner, _recipient, _mintedAmount);
    }
    
    // Modify the state of an account to 'frozen'
    function freezeAccount(address target, bool freeze) onlyOwner public {
        frozenAccount[target] = freeze;
        emit FrozenAccount(target, freeze);
    }
}