Automated spell checkers are used to analyze documents and locate words that might be misspelled. These programs work by comparing each word in the document to a large dictionary (in the non-Python sense) of words. If the word is not found in the dictionary, it is flagged as potentially incorrect.

Write a program to perform spell-checking on a text file. To do this, you will need to get a large file of English words in alphabetical order. If you have a Unix or Linux system available, you might poke around for a file called words, usually located in /usr/dict or /usr/share/dict. Otherwise, a quick search on the Internet should turn up something usable.
Your program should prompt for a file to analyze and then try to look up every word in the file using binary search. If a word is not found in the dictionary, print it on the screen as potentially incorrect.