your code has many issues ...

... a quick fix is to use push because it must already be in a loop

        $gate_type = $1;
        $gate_name = $2;
        $output_gate = $3;
        $input_A = $4;
        $input_B = $5;

        push @input_A, $input_A;  # column 2
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be warned that this will collect over all modules in your file.