Quick example:

@a = a..d;
@b = e..h;

($c, $d) = _ret_arr(\@a, \@b);

#print "@$c \t @$d $/";
#print "@a \t @b $/";

sub _ret_arr {
  my $a = shift;
  my $b = shift;
  my (@tmp_a, @tmp_b) = (@$a, @$b);

  # by reference
  #map{ $_ = uc }@$a,@$b;
  #return $a, $b;
  
  # by values
  #map { $_ = uc } @tmp_a, @tmp_b;
  #return \@tmp_a, \@$tmp_b
}
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Still perlref document is far more useful!