I followed the instructions here:   The error I got is below. Skype is not in my menu, I can't launch it, so must've failed.  Fetched 309 kB in 13s (22.2 kB/s) Reading package lists... Done W: The repository 'http://ppa.launchpad.net/eclipse-team/ppa/ubuntu xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://deb.opera.com/opera stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D615560BA5C7FF72 W: The repository 'http://archive.canonical.com/ubuntu saucy Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. W: Failed to fetch http://deb.opera.com/opera/dists/stable/InRelease  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D615560BA5C7FF72 E: Failed to fetch http://ppa.launchpad.net/eclipse-team/ppa/ubuntu/dists/xenial/main/binary-amd64/Packages  404  Not Found E: Failed to fetch http://archive.canonical.com/ubuntu/dists/saucy/partner/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1562::1c 80] W: Some index files failed to download. They have been ignored, or old ones used instead.
I want to install Skype, but I can't locate it in Software Center or by using Synaptic Package Manager. Can anyone help me?
Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:  def uniq(input):   output = []   for x in input:     if x not in output:       output.append(x)   return output   (Thanks to  for that .)  But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.  Related question: How can I remap keyboard keys in windows 8.1? I'm looking for a simple utility which will modify registry and would not require running at startup. I tried sharpkeys but, it does not seem to work in windows 8.1. Any other suggestions? Or a simple how-to tutorial for windows 8.1?  Edit: Keytweak isn't working either. Actually I want to map an unused key to function key (fn) and neither sharpkeys nor keytweak detect the keystroke for that key.   Thanks Everyone I speak to says that a 50mm lens is the best and beats them all as an all-rounder. I was wondering whether to get myself a decent, fast 50mm as well. However I'm still not 100% sure whether I really need such a lens.  I use a Pentax K10D and mainly shoot people (kids, portraits, some street shots). The lens I love and use most is the DA 70mm f/2.4 Limited. I often also use a DA 40mm f/2.8 Limited. They are great little lenses that produce very high quality images but they could be a bit faster.  Is is worth spending 400 quid on a Sigma 50mm f/1.4 in my situation? It seems like a good compromise between the 40mm and 70mm and much faster (in fact, 2 f-stops faster than the DA 70mm f/2.8!). On the other hand would the lens be sufficiently different from my current lenses? How can I prevent URLDownloadToFile from retrieving from the cache? I am using URLDownloadToFile to retrieve a file from a website. Subsequent calls return the original file rather than an updated version.  I assume it is retrieving a cached version. I've got a weird question. Assume that you have a small sample where the dependent variable that you're going to analyze with a simple linear model is highly left skewed. Thus you assume that $u$ is not normally distributed, because this would result in normally distributed $y$. But when you compute the QQ-Normal plot there is evidence, that the residuals are normally distributed. Thus anyone can assume that the error term is normally distributed, although $y$ is not. So what does it mean, when the error term seems to be normally distributed, but $y$ does not? Automatically show which tags were edited in revision history I’ve developed the habit of using the revision summary to indicate which changes I’ve made to the tags while retagging a question.  For instance, if the question originally had tags   and it should be  instead, I write the following in the revision summary:     Edited tags: -cocoa, -touch, +cocoa-touch   which I find useful (and potentially educational) for the OP and other editors.  On the other hand, when an editor doesn’t type a revision summary, Stack Overflow shows     User (timestamp) edited tags   with no indication of the difference between previous tags and the tags set by that edit.  Since there’s a limit on the number of tags, this difference would easily fit in the revision history list of that question. Could this be automatic in case the editor doesn’t fill the revision summary? Is it worth it? I am very confused. Unless I am mistaken, I know "it" has to be a noun of some sort, but I am unable to figure out what noun "it" is referring to.   What is "it" in the following sentence:      It is clear that Bob likes doughnuts.   Heres another couple of examples:     It is impossible to fly. How can I look at my character? Is there a way I can inspect my character's face at any point in the game after creating it during the bathroom scene?  I am playing on PlayStation 4 and rotating with the right stick in 3rd-person view obviously does not show the face. I haven't found any mirrors or shiny objects to use the reflection either.  The reason for this is that I forgot what she looks like and also I want to share my monstrous creation with others but I have already left the vault! Recommended books for advanced undergraduate electrodynamics What books are recommended for an advanced undergraduate course in electrodynamics? What happens when a familiar from the Find Familiar spell "dies"? I faced with a problem after update,   I missed 2 buttons from above panel, System menu (including shutdown, suspend &amp; …) and User (including log out &amp; …)  how can I restore them !?... 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