this syntax, somewhat amusingly, breaks on py2.6 *and* py3.3 (though for different reasons):

py2.6:

	Python 2.6.6 (r266:84374, Aug 31 2010, 11:00:51) 
	[GCC 4.0.1 (Apple Inc. build 5493)] on darwin
	Type "help", "copyright", "credits" or "license" for more information.
	>>> {i: 5 for i in range(5)}
	  File "<stdin>", line 1
	    {i: 5 for i in range(5)}
	            ^
	SyntaxError: invalid syntax


py3.3:

	Python 3.3.2 (default, Jun 30 2013, 23:23:11) 
	[GCC 4.2.1 Compatible Apple LLVM 4.2 (clang-425.0.24)] on darwin
	Type "help", "copyright", "credits" or "license" for more information.
	>>> {"a": "b"}.items() + {"c": "d"}.items()
	Traceback (most recent call last):
	  File "<stdin>", line 1, in <module>
	TypeError: unsupported operand type(s) for +: 'dict_items' and 'dict_items'