contract BurnableToken is StandardToken {

    /**
     * @dev Burns a specified amount of tokens.
     * @param _value The amount of tokens to burn. 
     */
    function burn(uint256 _value) public {
        require(_value > 0, "BurnableToken: value must be greterthan 0");

        address burner = msg.sender;
        balances[burner] = balances[burner].sub(_value);
        totalSupply = totalSupply.sub(_value);
        emit Transfer(msg.sender, address(0), _value);
    }
}
function burn(uint256 _value) public {
    require(_value > 0, "BurnableToken: value must be greterthan 0");

    address burner = msg.sender;
    balances[burner] = balances[burner].sub(_value);
    totalSupply = totalSupply.sub(_value);
    emit Transfer(msg.sender, address(0), _value);
}

/**
 * @dev Burns a specified amount of tokens.
 * @param _value The amount of tokens to burn. 
 */