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How does zip(*[iter(s)]*n) work in Python?
... each element is x. *arg unpacks a sequence into arguments for a function call. Therefore you're passing the same iterator 3 times to zip(), and it pulls an item from the iterator each time.
x = iter([1,2,3,4,5,6,7,8,9])
print zip(x, x, x)
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Mongodb Explain for Aggregation framework
...ther manipulation will be in-memory (possibly using temporary files if the allowDiskUse option is set).
Optimizing pipelines
In general, you can optimize aggregation pipelines by:
Starting a pipeline with a $match stage to restrict processing to relevant documents.
Ensuring the initial $match / ...
How to search DOM elements using XPath or CSS selectors in Chrome Developer Tools?
...ction accepts a second optional argument, context. $x(xpath, context) This allows you to select a particular iframe content, for example, and run an xpath query against it. So for the first iframe: myframe = document.getElementsByTagName("iframe")[0].contentWindow.document.body; #to xpath query that...
Can a JSON value contain a multiline string
...ate: And if you want to write newlines inside your JSON syntax without actually including newlines in the data, then you're even doubly out of luck. While JSON is intended to be human-friendly to a degree, it is still data and you're trying to apply arbitrary formatting to that data. That is absolut...
Should I URL-encode POST data?
I'm POSTing data to an external API (using PHP, if it's relevant).
4 Answers
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Reset Entity-Framework Migrations
... I used IgnoreChanges on the initial migration, but now I want to delete all my migrations and start with an initial migration with all of the logic.
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Pure virtual destructor in C++
...ing from A and then try to delete or destroy it, A's destructor will eventually be called. Since it is pure and doesn't have an implementation, undefined behavior will ensue. On one popular platform, that will invoke the purecall handler and crash.
Edit: fixing the declaration to be more conformant...
Print number of keys in Redis
... key. Also Redis may actively evict some expired keys, but not necessarily all of them.
– seppo0010
Aug 24 '15 at 22:23
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Rails: around_* callbacks
I have read the documentation at http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html , but don't understand when the around_* callbacks are triggered in relation to before_* and after_* .
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How can I expand the full path of the current file to pass to a command in Vim?
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How do you find these in VIM help?
– keflavich
Jan 25 '12 at 0:45
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