# Given:

 sub pair {
     my @out = ();
     for (my $i=0; $i<@_; $i+=2) {
         push(@out,[$_[$i],$_[$i+1]]);
     }
     return @out;
 }

# What is the value of the expression 

 map { &{$_->[1]}($_->[2]) ? $_->[0] : () }
 map { [$_->[0],$_->[1],'meowmoo'] } 
 &pair ( 'cat' => sub { $_[0] =~ /meow/ }, 
         'dog' => sub { $_[0] =~ /arf/ }, 
         'cow' => sub { $_[0] =~ /moo/ } )

# in an array context?