UnboundLocalError: local variable 'user_a' referenced before assignment
UnboundLocalError on local variable when reassigned after first use
Why directory with large amounts of entries does not shrink in size after entries are removed? Close vote notice: While the linked duplicate asks same question, the comments and the only answer do not provide an answer which draws from authoritative source. The , does in fact provide the answer I've been seeking. Thus the proposed duplicate isn't helpful, however Thomas's answer here is proper.  According to the  and personal account , directories that have large amount of entries get to a size over 4096 bytes (which can be seen with ls -l output), but once the entries are removed - the number never goes down.   The question is "why" ? Is it due to how ext4 filesystem configured to retain directory metadata ? Obviously removing the directory and recreating it isn't a solution, since it deletes original inode and creates a new one. What can be done to decrease the number manually ? Inverse of $y = x^3 + x $? Can you help me find the inverse function for $y = x^3 + x$?  This question was posed at the beginning of AP Calculus, so we can't use any math beyond precalc.  Thanks! If $$(1+ \cos A) (1+ \cos B) (1+\cos C)= y = (1- \cos A) (1-\cos B) (1-\cos C)$$ then prove that $$y = \pm \sin A \sin B \sin C$$ Does the plastic cap on a Presta valve serve any purpose once fitted to a rim? I can see the use of the valve cap on a Presta valve when the tube is still packaged (it obviously stops the valve puncturing the tube), but does it do anything except look pretty (or not) once you've fitted the tube to a rim?  I've kept them on out of habit, because I've had problems with sticking Schrader valves in the past when I've lost the caps and dirt/grime has got in there - but the design of Presta valves suggests to me that they wouldn't suffer this fate.  Given that I really need to , is replacing this cap something I can leave out of my daily chores? How to compute $\,3^{3^{3^{\:\!\phantom{}^{.^{.^.}}}}}\!\!\!\!\bmod 46,$ for power tower height $2020$? What is the remainder of $\,3^{3^{3^{\:\!\phantom{}^{.^{.^.}}}}}\!\!\!$ divided by $46$?  The level of powers is $2020$.  First there is no parenthesis so it means 3 power of 3 which is also power 3 and so on 2020 times  Second I think that we can use Fermat's Little Theorem but I don't know how, and maybe there is a better way. Why does Li+ ion move to cathode in Li-ion battery? I'm robotic engineer. I'm using OpenSCAD to model robotic components (gears, pulleys, parts, etc). But I need application to model physics and interaction of the components (for i.e. how will robot move if I will rotate current gear).  So, is it possible to import OpenSCAD models into Blender and model interactions in it?  I have models in STL format (for i.e. gears). I need to make reductor from it and see how it moves (if possible - measure rotation speed and torque). Grammatical number agreement in a complex phrase using singular "they" Object selection box with eyedropper Did the Big Bang happen at a point? ASP.NET MVC controller actions that return JSON or partial html How can I list the contents of a .zip folder in c#? How to factor intricate polynomial $ ab^3 - a^3b + a^3c -ac^3 +bc^3 - b^3c $ I would like to know how to factor the following polynomial.  $$ ab^3 - a^3b + a^3c -ac^3 +bc^3 - b^3c $$ What is the method I should use to factor it? If anyone could help.. Thanks in advance. "Where will you go" vs. "Where you will go" Which sentence is correct between these?      Where will you go?     Where you will go? Decreasing font size in verbatim How to create a color of the same brightness and saturation? Let's consider three colors: Red, Green and Blue. For blue I created a specific shade, something like #F2F5F7. If you see this color, it has a certain level of shade, brightness and saturation value of blue.  I want to create the same equivalent color but for Green and Red, how to get that? Is it possible to see own 'review queue audits' results? I completed recently a few review audits, some of them I passed, some I failed.  Is there a place I could (easily) find these results? In most electrical circuits with a relay, a diode is connected in parallel to the coil of the relay. Why? Is it always a good practice? Getting Started With Java EE I am about to start a web project and have been working almost exclusively with a LAMP stack for the past 5 years.  I would like to build something larger and more scalable and hence have been looking into Java EE.  The division of logic between JSP and EJB seems ideal for what I want to do.  Can anyone recommend resources for getting familiar with Java EE?  And perhaps if anyone knows of technologies that are more scalable than PHP that I should consider as well, I'm all ears.  Thanks a lot! Why did the Emperor remain motionless while Darth Vader threw him off the balcony? I'm wondering whether this was a movie sin but his body position seemed to stay the same? Also why didn't he stop using Force Lightning? He continued to use it even as he was falling down.   I'm also wondering whether Palpatine meant to electrocute Vader or was it just a coincidence (because he kept firing Force Lightning) .  It makes no sense as he just stood there allowing Vader to throw him.