This is in the first rule of Perl:

    grammar    :    GRAMPROG
                {
                  PL_parser->expect = XSTATE;
                }
            remember stmtseq
                {
                  newPROG(block_end($3,$4));
                  $$ = 0;
                }

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How can `$4` work when there're only `3` elements on the right side?

In reply to Where does $4 come from here? by PerlOnTheWay

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