py3: replace None with -1 to sort an integer array
In Python 2:
>>> ls = [4, 2, None]
>>> sorted(ls)
[None, 2, 4]
In Python 3:
>>> ls = [4, 2, None]
>>> sorted(ls)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unorderable types: NoneType() < int()
Therefore we replaced None with -1, and the safe part is that, None and -1 are
only the keys which are used for sorting so we don't need to convert the -1's
back to None.
Mercurial
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Mercurial is a fast, easy to use, distributed revision control tool
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Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing:
$ make local # build for inplace usage
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See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.