contract StandardToken is Token {
    /*
     *  Storage
    */
    mapping (address => uint) balances;
    mapping (address => mapping (address => uint)) allowances;

    /*
     *  Public functions
    */

    function transfer(address to, uint value) public returns (bool) {
        // Do not allow transfer to 0x0 or the token contract itself
        require((to != 0x0) && (to != address(this)));
        if (balances[msg.sender] < value)
            revert();  // Balance too low
        balances[msg.sender] -= value;
        balances[to] += value;
        Transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) public returns (bool) {
        // Do not allow transfer to 0x0 or the token contract itself
        require((to != 0x0) && (to != address(this)));
        if (balances[from] < value || allowances[from][msg.sender] < value)
            revert(); // Balance or allowance too low
        balances[to] += value;
        balances[from] -= value;
        allowances[from][msg.sender] -= value;
        Transfer(from, to, value);
        return true;
    }

    function approve(address spender, uint value) public returns (bool) {
        allowances[msg.sender][spender] = value;
        Approval(msg.sender, spender, value);
        return true;
    }

    function allowance(address owner, address spender) public constant returns (uint) {
        return allowances[owner][spender];
    }

    function balanceOf(address owner) public constant returns (uint) {
        return balances[owner];
    }
}
function transfer(address to, uint value) public returns (bool) {
    // Do not allow transfer to 0x0 or the token contract itself
    require((to != 0x0) && (to != address(this)));
    if (balances[msg.sender] < value)
        revert();  // Balance too low
    balances[msg.sender] -= value;
    balances[to] += value;
    Transfer(msg.sender, to, value);
    return true;
}

/*
 *  Public functions
 */