You can use a substitution code to encode a message. In this scheme, a key maps each letter to another letter. Each letter in the plain-text message is replaced according to the key to produce the encoded message, or cipher text. Suppose you are given some cipher text, but not the key. One method of breaking such a code is to count the frequency of letters in the cipher text and then make guesses about the mapping based on the frequencies of letters in typical English text. Write a program that reads characters from a file and uses a sorted list to find the frequency of each letter.