sub param {
    my($self,@p) = self_or_default(@_);
    return $self->all_parameters unless @p;
    my($name,$value,@other);
#~~~~~Snip~~~~~
    ($name,$value,@other) = rearrange([NAME,[DEFAULT,VALUE,VALUES]],@p);
#~~~~~Snip~~~~~
    return wantarray ? @{$self->{$name}} : $self->{$name}->[0];
}