# Copy a string, just to show how to do it.
def copyString(string):
    newString = ""
    for ch in string:
        newString = newString + ch
    return newString

# double each character in a string
def doubleString(string):
    newString = ""
    for ch in string:
        newString = newString + ch + ch
    return newString

# Reverse a string by constructing a new string.
def reverseString(string):
    newString = ""
    for ch in string:
        newString = ch + newString
    return newString

# encode a string with a deep, secret code
def encodeString(string):
    alphabet = "abcdefghijklmnopqrstuvwxyz "
    encoding = "nopqrstuvwxyzabcdefghijklm "

    string = string.lower()
    
    codedString = ""
    for ch in string:
        alphPos = alphabet.find(ch)
        codedString = codedString + encoding[alphPos]
    return codedString

# decode the string, using special magic
def decodeString(codeString):
    alphabet = "abcdefghijklmnopqrstuvwxyz "
    encoding = "nopqrstuvwxyzabcdefghijklm "
    
    decodedString = ""
    for ch in codeString:
        encodePos = encoding.find(ch)
        decodedString = decodedString + alphabet[encodePos]
    return decodedString