Regex isn't that fast

exact words out of my mouth lol

it helps to get off the computer and grab pen/paper and just work out the sudo code on paper first when things don't seem clear

Traceback (most recent call last):
File "tests.py", line 38, in
test.assert_equals(autocomplete('nothinghere', dictionaryNoGuess) , masterNoGuess('nothinghere', dictionaryNoGuess));
File "/workspace/default/solution.py", line 21, in autocomplete
if x == lower_y[i]:
IndexError: string index out of range

it seems like failed test case introduces a new variable 'dictionaryNoGuess'; empty dictionary variable
so my code fails.. I tried to check for it with len(dictionary) < 1 & sys.exit() but no luck

any advice?

it's a clean solution but regex solutions feel closer to best practice.

what do you think?