Iterating over a list in a function



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n = [3, 5, 7]

def total(numbers):
  result = 0
  for i in numbers:
    **result = numbers + 1**
    return result

I honestly do not know how this part works if someone can explain please.

Create a function that returns the sum of a list of numbers.

On line 3, define a function called total that accepts one argument called numbers. It will be a list.

Inside the function, create a variable called result and set it to zero.

Using one of the two methods above, iterate through the numbers list. For each number, add it to result.
Finally, return result.


We want to add each value to the result, in turn…

result += i

Be sure that the return statement is not inside the loop.


Thank you for your help.
One thing I am struggling with is trying to understand the loop. I know how to define a function
def and make and argument(). I also know how to create a loop
for, in.

I don’t know f you could explain to me how this part works
result += i
what does it do? I understand >=, !=, >, <, <= but +=? this does not make sense to me.

Thank you.


Those are all comparison operators.


is a compound assignment operator. Consider the following:

result = result + i

In the above, a new value is created using both result and i. This new value is then assigned back to the original variable, replacing its old value with the new one. We can do this two step process with a single operator…

result += i

The process is identical to the one above, only shortened to make the code more readable.

Any math operator can be written in compound form.


are the most common, but we can also write compound form of,


We can even use the compound form on bitwise operators (but you will rarely see this).


The main thing to keep in mind is that the variable on the left is being re-assigned with the new value.

>>> a = 12
>>> a <<= 2
>>> a
>>> a >>= 2
>>> a


Now it makes more sense.
Thank you.


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