I need help in Python. Also, preferebly Python3

The U.S. Code of Conduct outlines the way service members are to act if they are captured during war. Article III of the Code of Conduct is as follows: If I am captured I will continue to resist by all means available. I will make every effort to escape and to aid others to escape. I will accept neither parole nor special favors from the enemy. " If POWs are unable to escape, they may at least be able to pass information back to their country to detail POW camp conditions, relay intelligence, or request support. One such attempt involved U.S. Navy Rear Admiral Jeremiah Denton blinking "TORTURE" during a coerced television interview as a captured POW during the Vietnam War. Though he said that they were well fed and well clothed, he was able to convey that he was speaking under duress and continue to resist despite the terrible conditions he and his fellow prisoners faced. Here is a video of his coerced TV interview: https: //www.youtube.com/watch?v=rufnWLVQcKq A different incident from World War 2 involved a British Prisoner of War who encoded messages into innocuous letters home. The messages hidden in these letters had to make their way through the German censors before making it home, so they must have been well hidden: http: //www.bbc.comews/uk-enaland-22357713 The file POW letter.txt is a fictitious letter home from a POW that contains a hidden message. This message is hidden by starting at some point in the letter and selecting every 21st letter. You know the letter spacing is 21, but you do not know where he started. Write a function called find_hidden_message () which takes two inputs: the filename which you would like to open, and the starting letter index. Read the file whose name was passed into your function into Python using file I/O. Remove all spaces, newlines, punctuation, and capitalization from the contents of the file. Return the string which is comprised of selecting every 21st letter starting at the starting index. Uncovering the hidden message will take some trial and error, but eventually, you should be find the hidden message by looking at the output. Include and fill out the comments after the doctest strings specifying what the starting index of the message was and finally, what the secret message was. > > > find_hidden_message("POW_letter.txt", 0) 'mwoyarahwttenoptlsleulwwtiynvyllo' > > > find_hidden_message("POW_letter.txt", 1) 'yaupbnycorutdclhysdbsyiitvoeefiyu' > > > find_hidden_message("POW_letter.txt", 18) 'aluraroodrsmeeceitveekulneuspnel' # Secret message begins at index: # Secret message is