I am now focusing on Data Visualization with Matplotlib, and the issue I mentioned really distracts me while practicing on Python.
There is no problem after running the code. I can get expected results. Although two files are in the same directory without any typos, Visual Studio lists the following warning all the time:
import "random_wall" could not be resolved
There was a link which opened github when I clicked the first time, but now the link is not there any more.
I upload two images to help you understand my problem visually. Thanks in advance.