Python List Coding Exercise - How do I repeat the same operation three times within a nested function?

Question

I am working on a list exercise in Python where I am creating a function that appends the sum of the last two numbers in a list. Then I need to repeat the process two more times using the new list created by the first returned result.

I have the first part right and I can get the code to add the first value to the list. The problem is I can't figure out how to repeat the process two more times.

Here is what I have;

#This section adds the last two numbers together and appends to lst
  lst.append(lst[-1] + lst[-2])
  return lst

#I tried doing this but it produced the exact same result
  lst.append(lst[-1] + lst[-2])
  return lst
  lst.append(lst[-1] + lst[-2])
  return lst

#Uncomment the line below when your function is done
print(append_sum([1, 1, 2]))

#After I run the code I get
[1, 1, 2, 3]

Answer 1

This is because you return the list after your first call, thus the second two calls don't happen.

Just replace your calls with a for loop as follows and you should be fine:

def list_sum(lst):
    for _ in range(3):
        lst.append(lst[-1] + lst[-2])
    return lst
    
print(list_sum([1,1,2]))

(this prints [1,1,2,3,5,8] )