How to check if a list exists in Python

Question

What is the easiest way to check to see if a list or dict exists in python ?

Im using the following but this isn't working:

if len(list) == 0:
    print "Im not here"

Thanks,

user_4038384 · Answer

s = set([1, 2, 3, 4])
if 3 in s:
    print("The number 3 is in the list.")
else:
    print("The number 3 is NOT in the list.")