Recently, I have been in trouble about this problem.

Last Friday midnight(early Saturday morning to be precise), I completed the code that "should be worked" I expected and went to bed.

If I would try to execute the program, I should have started debugging for all night, and I confirmed that I was convinced that I would get sick.

Therefore, I was very happy that I confirmed the program worked well with just two modifications.

I uploaded this program to AWS (correctly, Amazon Lightsail, a low-cost version of AWS) and continued the test run.

Anyway, I could confirm that this program is working as a server, I am going to ask my workers and students to do the test run.

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The reason I am trying to make the server, is not for work but for my interest.

No one ordered me to do that, it is just that my intuition is telling me "this wil make my work easier in the future"