If you are looking at using the the python version of the LittleArm GUI, there are a couple of considerations. The first, which will be discussed in this post, is called a dependency.
Dependencies are side programs which a particular piece of software needs in order to operate. For example your Windows operating system has a dependency on some type of browser such as Explorer or Chrome in order to update itself. Without that extra software the program won't work correctly. The LittleArm GUI has similar requirements.
Now, most python programs begin with the importing of the dependencies. These are lines of code in the program which tell the computer what dependencies need to be made available for the program. These lines of code for the LittleArm GUI are shown below.
Every one of those "import" statements calls one of the dependencies. But here is the kicker, if those dependencies are not installed on your computer, then the program will not run.
So you have to install the dependencies for the LittleArm GUI. In this case the only one you need is pyserial which is called in the fourth and fifth lines. The the first three statements import the "time" and Tkinter modules. Both of those modules come with any installation of python.
If you install the the latest version of pyserial, the module that allows python to use your computer communication ports, the LittleArm GUI should run just fine.