[Tutor] Problem with code interating thri a list

[Chris Clifton]

Hello Everyone,
   I have been practicing with strings.  Splitting them, joining them, changing case.  All has been going well but came across a exercise in one of the code practice sites that has you changing the case of different characters in a string.  Anything in upper case is converted to lower case and anything in lower case is converted to upper.  The solution I have created seems to work but I have not been able to figure out how to join the string back together.   String I'm using is "This Is A Test!" to be changed to "tHIS iS a tEST!".  

My Logic:  Since a string is immutable, I converted it to a list to separate out the characters and keep them in order.  Idea is to change the case of the characters in the list then run a join to convert it back to a string.

Can you point me in the right direction?

the print statements in the code are for my debugging and will be removed in the end. 
Python 3.5.1 on Windows 10.---------------------------------------------------------------------
# Create a function that will take a string and change the upper case characters to lower
# and the lower case characters to upper.

# Create a function.
def convert(text):
    print(text)
    text = list(text)
# Convert string to a list to separate/split characters and maintain order.
    print(text)
# Check case and convert to opposite case.
    for item in text:
        if item == item.lower():
            item = item.upper()
            print(item)
        else:
            item = item.lower()
            print(item)
# Convert list back into string with .join.
        result = "".join(text)
    print()
    print(result)
    return result

# Call the function
print(convert("This Is A Test!"))
-----------------------------------------------------------------------------
Thanks,Chris Clifton