Method operator ==

code/mathematics/berlekamp_massey.test.cpp:24–26

        return x * mod_inv(other.x, 1000000007);
    }
    bool operator ==(const Mod &other) const {
        return x == other.x;
    }
};
ostream& operator <<(ostream &outs, const Mod &x) {
    return outs << x.x;