[docs] Backport set and dictionary comprehensions in tutorial to 2.7 (issue 16470)

[fossilet at users.sourceforge.net]

http://bugs.python.org/review/16470/diff/6577/Doc/tutorial/datastructures.rst
File Doc/tutorial/datastructures.rst (right):

http://bugs.python.org/review/16470/diff/6577/Doc/tutorial/datastructures.rst#newcode520
Doc/tutorial/datastructures.rst:520: Like :ref:`for lists
<tut-listcomps>`, there is a set comprehension syntax::
Sounds good.  Will this rephrasing also be applied to 3.x?
On 2012/11/14 09:32:19, ezio.melotti wrote:
> The first part of the sentence doesn't sound too good to me.
> Maybe it could be rephrased to something like "Similarly to list
comprehensions,
> set comprehensions are also supported::"

http://bugs.python.org/review/16470/