[Python] List does not working in item List

When I try to pick the item I want, I could not create a List.
But if it is just in range, it works fine.
Like following code, Could any method to solve this??

aa = []
bb = []
for item in self.findItems():
    aa += [2]

bb = [2 for itme in self.findItems()]

self.say(aa) # say []    
self.say(bb) # say []

for i in range(4):
    aa += [2]

self.say(aa) # say [2, 2, 2, 2]

Perhaps self.findItems() is returning an empty list? So you get zero iterations and your resulting list is empty.

By double Checking.

I find that if it’s in the for loop, it would be wrong as following code.

for i in range(1):
    items = [item for item in self.findItems() if True]
    self.say(items)

But If I put it outside the for loop, it works fine.

items = [item for item in self.findItems() if True]
self.say(items)