How abstract do you want it?

ref($this) ne 'Pipe';
ref($_) ne 'Pipe';     # $_ is a topicaliser, so is "this" - thus, "th
+is" == "$_"
! UNIVERSAL::can($this, 'smoke');
$_->can('smoke');
[download]

Perl 6 ok?

!.isa('Pipe');
[download]

Just wondering.

Update: Missed the ! on the perl6 code.