Why not 3.__class__ ?

[Guido van Rossum]

Marcin, I don't understand why you care so much about being able to
write 3.foo.  It's painful to fix in the lexer, and probably leads to
less useful error messages if someone makes a mistake in a float
literal (e.g. "3.e 0").  And I see zero use for it: in practice, you
will never ask for 3.foo -- you'll ask for x.foo where x happens to
contain the value 3.

--Guido van Rossum (home page: http://www.python.org/~guido/)