perl -le 'use strict;my @a=("a");@a=();print "Defined" if defined @a;print scalar @a'

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perl -le 'use strict;my @a=("a");undef @a;print "Defined" if defined @a;print scalar @a'

##</code><code>##

perl -le 'use strict;my @a=("a");@a=undef;print "Defined" if defined @a;print scalar @a'