contract ReadOnlyTokenImpl is ReadOnlyToken {
    mapping(address => uint256) balances;
    mapping(address => mapping(address => uint256)) internal allowed;

    /**
    * @dev Gets the balance of the specified address.
    * @param _owner The address to query the the balance of.
    * @return An uint256 representing the amount owned by the passed address.
    */
    function balanceOf(address _owner) public constant returns (uint256 balance) {
        return balances[_owner];
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param _owner address The address which owns the funds.
     * @param _spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
}
function balanceOf(address _owner) public constant returns (uint256 balance) {
    return balances[_owner];
}

/**
 * @dev Gets the balance of the specified address.
 * @param _owner The address to query the the balance of.
 * @return An uint256 representing the amount owned by the passed address.
 */