def getNumber(low, high, prompt="Enter a number: "):
    number=low-1
    while number<low or number>high:
        numberString=input(prompt)
        try:
            number=int(numberString)
        except ValueError:
            print("That is not a valid number")
    return number

def compress():
    file1 = open("words.txt", "w")
    file2 = open("positions.txt", "w")
    sentence = input("What is your sentence?: ")
    sentence = sentence.split()
    words = sentence
    positions = [0]
    uniqueWords = []
    for i in words:
        if i not in uniqueWords:
            uniqueWords.append(i)
    uniqueWords = " ".join(uniqueWords)
    file1.write(uniqueWords)
    file1.close()
    for count, i in enumerate(sentence): 
        if sentence.count(i) < 2:
            positions.append(max(positions) + 1)
        else:
            positions.append(sentence.index(i) + 1)    
    positions.remove(0)
    positions = " ".join(map(str, positions))
    file2.write(positions)
    file2.close()
    print("Check your folder")
    return

def decompress():
    global positions
    global uniqueWords
    uniqueWords = uniqueWords.split()
    newSentence = []
    positions = list(map(int,positions.split()))
    file3 = open("original.txt","w")
    for i in positions:
        newSentence.append(uniqueWords[i-1])
    newSentence = " ".join(newSentence)
    file3.write(newSentence)
    file3.close()
    return

loop = True
while loop:
    print("\nTask3 Menu\n1. Compress a sentence\n2. Decompress a sentence\n3. End the program")
    choice = getNumber(1,3,"Enter your choice (1,2 or 3): ")
    if choice == 1:
        compress()
    elif choice == 2:
        decompress()
    else:
        loop = False
        print("Program ending...")

Error:
Traceback (most recent call last):
  File "//HUHTA-FPS0001/Claitusers$/huhta-clait53/documents/Phillip Holmes/Programs/Task3/Task3v7.py", line 58, in <module>
    decompress()
  File "//HUHTA-FPS0001/Claitusers$/huhta-clait53/documents/Phillip Holmes/Programs/Task3/Task3v7.py", line 40, in decompress
    uniqueWords = uniqueWords.split()
NameError: name 'uniqueWords' is not defined

def reverse():
    global positions
    global uniqueWords
    uniqueWords = uniqueWords.split()
    newSentence = []
    positions = list(map(int,positions.split()))
    file3 = open("original.txt","w")
    for i in positions:
        newSentence.append(uniqueWords[i-1])
    newSentence = " ".join(newSentence)
    file3.write(newSentence)
    file3.close()
    return
file1 = open("words.txt", "w")
file2 = open("positions.txt", "w")
sentence = input("What is your sentence?: ")
sentence = sentence.split()
words = sentence
positions = [0]
uniqueWords = []
for i in words:
    if i not in uniqueWords:
        uniqueWords.append(i)
uniqueWords = " ".join(uniqueWords)
file1.write(uniqueWords)
file1.close()
for count, i in enumerate(sentence): 
    if sentence.count(i) < 2:
        positions.append(max(positions) + 1)
    else:
        positions.append(sentence.index(i) + 1)    
positions.remove(0)
positions = " ".join(map(str, positions))
file2.write(positions)
file2.close()
option = input("Would you like to convert your sentence back to its original form? ")
if option in ["yEs","yeS","yES","YEs","Yes","yes","YES","y","Y"]:
    reverse()

Quote:NameError: name 'uniqueWords' is not defined