Actually that is invalid because exists doesn't operate on scalars.

exists argument is not a HASH or ARRAY element or a subroutine at ...

The valid equivalent of that is defined $a && defined $b but don't use $a and $b outside of a sort.

In reply to Re^2: why can't compare a variable with undef directly? by Mr. Muskrat
in thread why can't compare a variable with undef directly? by Anonymous Monk

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