Are "proper" closures used in Emacs sources?

[Marcin Borkowski]

Hi all,

it's been quite some time since lexical binding was introduced to
Elisp.  Apart from possible optimizations and being less error-prone, it
allows for all the cool tricks with closures.  Are there any places in
Emacs core where "proper" closures are actually used?  (By "proper",
I mean closures with non-empty lexical environment, actually using said
environment.)

TIA,

-- 
Marcin Borkowski
http://mbork.pl