sub get_data {
   ...;
   return;   # undef in scalar context or the empty list in list context
}

##</code><code>##

sub get_data {
   ...;
   return undef;   # undef in scalar context and a one-item list containing undef in list context
}

##</code><code>##

  sub enable_warnings {
    my $self = shift;
    $self->{warnings} = 1;
    return $self;
  }
  sub enable_errors {
    my $self = shift;
    $self->{errors} = 1;
    return $self;
  }
  sub disable_warnings {
    my $self = shift;
    $self->{warnings} = 0;
    return $self;
  }
  sub disable_errors {
    my $self = shift;
    $self->{errors} = 0;
    return $self;
  }
  sub run_process {
    my $self = shift;
    ...;
    return $result;
  }

# Now instead of doing this:

$widget->enable_warnings;
$widget->enable_errors;
my $result = $widget->run_process;

# We can do this:

my $result = $widget->enable_warnings->enable_errors->run_process;

##</code><code>##

sub bleh {
  return $result;
}

##</code><code>##

sub bleh {
  $result;
}