f(h, levelToPrint, currentLevel) {
    if (currentLevel > levelToPrint) return 0;
    if (!h) {
        if (currentLevel == levelToPrint) print("(null)");
        return 0;
    }
    if (currentLevel == levelToPrint) {
        print(h);
        return 1;
    }
    return f(h.left,levelToPrint, currentLevel+1) + f(h.right,levelToPrint, currentLevel+1);
}

levelToPrint=0;
while (f(tree,levelToPrint++,0)) print("\n");

f(h, level) {
    if (level == 0) print(h); // h might be null
    return h && level >= 0 ? level==0 ? 1 : f(h.left,level-1) + f(h.right,level-1) : 0;
}

l=0;
while (f(tree,l++)) print("\n");

f(h, level) {
    if (level < 0) return 0;
    if (!h) {
        if (level == 0) print("(null)");
        return 0;
    }
    if (level == 0) {
        print(h);
        return 1;
    }
    return f(h.left,level-1) + f(h.right,level-1);
}

l=0;
while (f(tree,l++)) print("\n");

class delay {
    double *m_buf;
    int m_len,m_pos;
public:
    delay(int len) { m_len=len; m_buf=(double*)calloc(sizeof(double),len); m_pos=0; }
    ~delay() { free(m_buf); }
    double process(double in) {
        double ret=m_buf[m_pos];
        m_buf[m_pos]=in;
        if (++m_pos>=m_len) m_pos=0;
        return ret;
    }
};