Regarding not declaring variables in Python...

If you're referring to:

x = 2 #OR
y = 'FooBar'

then, you're correct in noting that you don't need to declare them before giving them values. However, with regards to the following, the variable 'n' must have a value for the statement to execute at all:

print(n if n is None else 'Bummer')

Even JavaScript has gotten more strict about things. If a variable is not defined before its value is retrieved, an error/exception/whatever is raised. Note that this behaviour is only caused by not having a value for the variable when its non-existent getter function is called (after all, how can you retrieve something if it doesn't exist!?). You can assign a value such as undefined (JavaScript) or None (Python) just fine. Then things will work.

QB seems rather unique in the fact that you can just use the following readily:
IF n = 0 THEN PRINT n ELSE PRINT "Bummer"

That is perfectly acceptable in QB, which is very strange compared to many other languages I've used to create programs.