sub ideal
    # Everything must be declared before use or at definition
    while INPUT
        $accumulator .= $obj->do_something( $_ )

    return $result

sub reality
    # Allow the use of things prior to declaring or defining them: one pass
    # looks for all declarations and the next pass proceeds as normal.
    @input = INPUT
    $obj->examine( @input )

    while @input
        $accumulator .= $obj->do_something( $_ )

    return $result

sub surreality
    # Just like reality() except that post-facto declarations might change
    # how previous results in $accumulator occurred.
    while INPUT
        $accumulator .= $obj->do_something( $_ )

    return $result