pprint: "...thank small children who sleep at night."

[Brian L. Troutwine]

The heading comment to pprint reads:

#  This is a simple little module I wrote to make life easier.  I
didn't
#  see anything quite like it in the library, though I may have
overlooked
#  something.  I wrote this when I was trying to read some heavily
nested
#  tuples with fairly non-descriptive content.  This is modeled very
much
#  after Lisp/Scheme - style pretty-printing of lists.  If you find it
#  useful, thank small children who sleep at night.

Is the last sentence an obscure reference or in-joke? Can someone
explain it? I don't get it.