@Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        @SuppressWarnings("rawtypes")
        Pair other = (Pair) obj;
        if (h == null) {
            if (other.h != null)
                return false;
        } else if (!h.equals(other.h))
            return false;
        if (t == null) {
            if (other.t != null)
                return false;
        } else if (!t.equals(other.t))
            return false;
        return true;
    }