import extensions;

public FibonacciGenerator
{
    yieldable next()
    {
        long n_2 := 1l;
        long n_1 := 1l;

        $yield n_2;
        $yield n_1;

        while(true)
        {
            long n := n_2 + n_1;

            $yield n;

            n_2 := n_1;
            n_1 := n
        }
    }
}

public program()
{
    auto e := new FibonacciGenerator();

    for(int i := 0, i < 10, i += 1) {
        console.printLine(e.next())
    };

    console.readChar()
}