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 w1,w2,w3,w4;

    not_gate u1(b,w1);
    not_gate u2(a,w2);
    and_gate u3(a,w1,w3);
    and_gate u4(b,w2,w4);
    or_gate  u5(w3,w4,y);

endmodule