// test_simulation_xor_1_test.v
module f1_test(input [1:0] in, output out);
assign out = (in[0] ^ in[1]);
endmodule

// test_simulation_xor_2_test.v
module f2_test(input [2:0] in, output out);
assign out = (in[0] ^ in[1] ^ in[2]);
endmodule

// test_simulation_xor_3_test.v
module f3_test(input [3:0] in, output out);
assign out = (in[0] ^ in[1] ^ in[2] ^ in[3]);
endmodule

// test_simulation_xor_4_test.v
module f4_test(input [3:0] in, output out);
xor myxor(out, in[0], in[1], in[2], in[3]);
endmodule