I was reading the Python documentation on lists and saw:     list.extend(L) Extend the list by appending all the items in the given list. Equivalent to: a[len(a):] = L.   I was wondering where I could read about the : colon to fully understand it. Python documentation for 3.4 would be very helpful.
I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.
In a perfect world, the so-important advice "do not reinvent the wheel" would be extensively followed. In practice, everyday millions of wheels are reinvented simply because someone didn't know an existing solution for a specific problem. The best way to find a library, today, is googling it, but it's not always obvious which keywords to use. The lack of a tool for finding solutions is very counterproductive for the dev world as a whole. Stack Overflow is not very receptive for recommendation threads. So what about a new SE for it? Should questions include "tags" in their titles? I've seen questions edited to remove the language name from the title. Won't search engines - and folks using search engines - have an easier time finding them if these "tags" are kept as part of the title? How to check if current thread is not main thread Why draw blood from veins rather than arteries? Why draw blood from veins rather than arteries? Is it more convenient or safer? Is there any Sound enhancers/equalizer? My Ubuntu version 18.04 brings me a GNU GRUB version 2.02 and I cannot access my entry password panel? $(m, m+2)$ is twin prime, iff $4((m-1)! + 1) \equiv -m \pmod {m(m+2)}$ The Wiki page on  says     The pair $(m, m+2)$ is twin prime, iff $4((m-1)! + 1) \equiv -m \pmod {m(m+2)}$.   This is obviously connected to Wilson's Theorem. Can anybody provide a proof for that, along the lines of thought given here, ? Access to original contents of mount point This is a question you can read everywhere on the web with various answers:  $ext = end(explode('.', $filename)); $ext = substr(strrchr($filename, '.'), 1); $ext = substr($filename, strrpos($filename, '.') + 1); $ext = preg_replace('/^.*\.([^.]+)$/D', '$1', $filename);  $exts = split("[/\\.]", $filename); $n    = count($exts)-1; $ext  = $exts[$n];   etc.  However, there is always "the best way" and it should be on Stack Overflow. Lots of new batteries (for mobile devices, MP3 players, etc) have connectors with 3 pins. I would like to know what is the purpose of this and how should I use these three pins?    They are usually marked as (+) plus, (-) minus, and T. How can I list the contents of a .zip folder in c#? How to use the SSD for caching in Windows without Intel Smart Response? My motherboard is Asus P8B75-M. It doesn't have Intel Smart Response. But recently I bought a SSD. Since I mostly use linux I have Linux installed in it. But can I use it to speed up Windows also? How? I don't have Smart Response... (I run Windows 8.1). The SSD is only 64GB. Finding all solutions for a system of equations with constraint on the sum of absolute values I am looking for a fast algorithm to find all integer solutions for the following system of linear equations ($c_1,\ldots,c_n \in \mathbb{Z}$ and $r\in \mathbb{N}$ ):  $x_1+x_2=c_1$  $x_3+x_4=c_2$  ...  $x_{2n-1}+x_{2n}=c_n$  $|x_1|+|x_2|+\ldots+|x_{2n}|=r$  $x_1,\ldots,x_{2n} \in \mathbb{Z}$   Also can we find the number of solutions before solving the system? How precisely do I need to post close to 7:00 (somewhere) to get hero of time? Timezones... are complicated. We have full hour offsets, half hour offsets...  And time keeping isn't always accurate. So does the Hero Of Time hat assume full or half hour offsets (or literally any timezone) and how close to 7:00 at somewhere do I have to post for my hat? Downgrading from Safari 12 (beta) to Safari 11 Installing Safari beta version is apparently only possible by replacing the builtin Safari version. In this case version 11.1.2 with 12. If beta version does not work, gives too much trouble or is just unpleasant:  How do we downgrade to an official stable version, currently Safari 11.1.2 for 10.12.6 Sierra?  I tried to restore everything relating to 11.1.2 from a backup (going by what is found that is in the installer package), I located and re-applied the 11.1.2_Sierra.pkg. Yet Safari now refuses to work entirely.   Crashed Thread:        3  Dispatch queue: com.apple.SafariCore.RemotePlistController.internalQueue  Exception Type:        EXC_CRASH (SIGABRT) Exception Codes:       0x0000000000000000, 0x0000000000000000 Exception Note:        EXC_CORPSE_NOTIFY  Application Specific Information: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[_NSPlaceholderData initWithContentsOfURL:options:error:]: nil URL argument' terminating with uncaught exception of type NSException abort() called   Is there any way around re-installing the entire system? Easy way to disable a UITextField? Is there an easy way to disable a UITextField in code?  My app has 12 UITextField that are all turned on by default, but when a change is detected in my Segment Control I want to disable some of the UITextField depending on what Segment the user picks.  Just need to know how to disable it or make it non-editable?  Thanks Please add a system to allow file uploads attached to questions and answers I posted a question and a couple of respondents asked for the source code. I could only post portions of the code.  If attachments were allowed I could have uploaded a .zip file with the whole application.  Will this be a feature in SO? How do I identify which CPU a MacBook uses? I'd like to identify which CPU this notebook is using, in terms of code names such as "Ivy Bridge" and "Haswell". The little Apple logo in the upper left shows some information, but not this. Flight reservation for Schengen visa One of the necessary documents for a Schengen visa for non EU citizens is proof of your flights, but it doesn't state the actual (e-)tickets (for which I already paid), or the reservation of flights.  So my question is, which option would be more acceptable (if I can provide any of them) to provide printed tickets to an EU member embassy or reservation of flights (reservation does not expect payment)? How to match * with hidden files inside a directory How to match the hidden files inside the given directories   for example   If I give the below command it's not giving the result of the hidden files,     du -b maybehere*/*   how to achieve this simple using a single command instead of using   du -b maybehere*/.* maybehere*/*   as I need to type maybehere twice.