Consider the following example
b = a.split(',')
The behaviour of
a.split(',') when no commas are present in
a is perfectly consistent with the way it behaves when there are a positive number of commas in
a.split(',') says to split string
a into a list of substrings that are delimited by
a; the delimiter is not preserved in the substrings.
If 1 comma is found you get 2 substrings in the list, if 2 commas are found you get 3 substrings in the list, and in general, if n commas are found you get n+1 substrings in the list. So if 0 commas are found you get 1 substring in the list.
If you want 0 substrings in the list, then you'll need to supply a string with -1 commas in it. Good luck with that. :)