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Python Python Basics (Retired) Putting the "Fun" Back in "Function" Functions

Posted by Erik Courtney
Erik Courtney
2,543 Points

Functions add_list and summarize work everywhere else but your code interpreter.

in challenge task 2 of 2, I'm unable to get two functions to execute properly. This code and minor variations I have tried will run on several other interpreters I've tried. Any ideas?

functions.py 
# add_list([1, 2, 3]) should return 6
# summarize([1, 2, 3]) should return "The sum of [1, 2, 3] is 6."
# Note: both functions will only take *one* argument each.
def add_list(items):
  total = 0
  for i in items:
    total = total + i
  return total

def summarize(lst):
  ntotal = add_list(lst)
  print("the sum of %s is %s." % (lst, ntotal))

3 Answers

Erik Courtney
Erik Courtney
2,543 Points
Erik Courtney
Erik Courtney
2,543 Points

Thanks, I think it was looking for a return and not a print. Though the error AttributeError: 'NoneType' object has no attribute 'lower'" didn't really help on that front.

Replacing print with return worked fine with original code as well.

Tree Casiano
Tree Casiano
16,436 Points

That make sense. Glad you got it to work.

Tree Casiano
Tree Casiano
16,436 Points
Tree Casiano
Tree Casiano
16,436 Points

In the summarize function, I was able to get the code to pass by using string formatting, like so: 

def add_list(items):
  total = 0
  for i in items:
    total = total + i
  return total

def summarize(items):
  return "The sum of {} is {}".format(str(items), sum(items))

I'm not sure why your original code would run elsewhere and not here unless it has to do with different versions of Python.

Kenneth Love
STAFF
Kenneth Love
Treehouse Guest Teacher
Kenneth Love
Kenneth Love
Treehouse Guest Teacher

Yeah, you have to return from functions in code challenges (really, you'll probably want to do this 99.9999% of the time anyway). The NoneType error comes from the fact that I got nothing back from your function (or, rather, I got None) which doesn't have a .lower() method.