If you slice sequences by specifying out of bound index, it will slice the sequence to nearest index

How come this doesn't raise an IndexError ("list index out of bounds") in Python, as soon as i reaches len(arr)?

I did not know you could slice arrays with indices larger than the array length...

I was trying to figure out how this one worked, since the array indexes seem off - but it's just adding the "middle" number (arr[i]) to both the left and the right sum() (which refer to the right and the left halves of arr, respectively).