package C;
  our @ISA = qw/ A /;
  sub 123 {
    my $self = shift;
    # let my superclass do its thing first
    my $result = $self->SUPER::123(@_);
    # now I'll do a bit
    ...
  }

##</code><code>##

  sub 123 {
    my $self = shift;
    my(@array, $scalar);
    if (wantarray) {
      @array = $self->SUPER::123(@_);
    } elsif (defined wantarray) {
      $scalar = $self->SUPER::123(@_);
    } else {
      $self->SUPER::123(@_);
    }
    # do more stuff
    return wantarray ? @array : $scalar;
  }