9. XOR Gate Using Basic Gates

How do you plan to solve it?

// ============================================================
// Basic Gates (given)
// ============================================================
module and_gate(input a, b, output y);
    assign y = a & b;
endmodule

module or_gate(input a, b, output y);
    assign y = a | b;

endmodule

module not_gate(input a, output y);
    assign y = ~a;

endmodule

// ============================================================
// XOR Gate
// ============================================================
module xor_gate (
    input  a, b,
    output y
);
    wire y0, y1, y2, y3;

    not_gate not1 (
        .a(b),
        .y(y0)
    );

    and_gate and1 (
        .a(a),
        .b(y0),
        .y(y1)
    );

    not_gate not2 (
        .a(a),
        .y(y2)
    );

    and_gate and2 (
        .a(y2),
        .b(b),
        .y(y3)
    );

    or_gate or1 (
        .a(y1),
        .b(y3),
        .y(y)
    );

endmodule