Python: need to create a program that decodes caesar ciphers and meets the following requirements
1. Input the cipher-text.
2. Find the most common character.
3. Find the shift from "E" to that most common character.
4. Use the shift to decode each character of the cipher-text and print the resulting plain-text.
6. If the plain-text isn't readable English, try the next-most common character and continue checking successive next-most-common characters until the resulting plain-text is readable.
7. uses get_char, get_shift, output_plaintext functions