references.txt

The main source is: https://docs.python.org/3/tutorial/ 
I used it for almost each of the statements that I wrote 

Also useful:
- https://www.tutorialspoint.com/python/python_basic_operators.htm

Additional sources:
 - https://stackoverflow.com/questions/4841436/what-exactly-does-do-in-python
 - https://stackoverflow.com/questions/159720/what-is-the-naming-convention-in-python-for-variable-and-function-names
 - https://www.pythoncentral.io/how-to-generate-a-random-number-in-python/
 - https://www.pythonforbeginners.com/basics/getting-user-input-from-the-keyboard
 - https://anh.cs.luc.edu/python/hands-on/3.1/handsonHtml/io.html
 - https://www.hackerearth.com/practice/python/getting-started/input-and-output/tutorial/
 - https://pypi.org/project/getch/
 - https://stackoverflow.com/questions/983354/how-do-i-make-python-to-wait-for-a-pressed-key
 I tried the msvcrt.getch from above, but could not bring it to work... hence I used (revert to) the python 'input' method.
 
 - https://www.programiz.com/python-programming/keyword-list
 - https://introcs.cs.princeton.edu/python/appendix_precedence/
 - https://www.programiz.com/python-programming/examples/odd-even
 - http://interactivepython.org/runestone/static/pip2/Functions/Returningavaluefromafunction.html
 - 
 
 - https://stackoverflow.com/questions/9202224/getting-command-line-password-input-in-python
 - https://www.pythonforbeginners.com/files/reading-and-writing-files-in-python
 - https://www.tutorialspoint.com/python/python_strings.htm
 - https://www.programiz.com/python-programming/dictionary
 - https://stackoverflow.com/questions/1047318/easiest-way-to-persist-a-data-structure-to-a-file-in-python 
 - https://docs.python.org/3/library/pickle.html
 - https://wiki.python.org/moin/UsingPickle
 - https://pythontips.com/2013/08/02/what-is-pickle-in-python/
 - https://visualgit.readthedocs.io/en/latest/pages/naming_convention.html
 - https://stackoverflow.com/questions/38878741/getpasswarning-can-not-control-echo-on-the-terminal-when-running-from-idle