######## a.py ########
aa = "Hello World"
####### b.py ########
from a import aa
print aa #OK
print a.aa #ERROR, there will be error "a" is not defined
######## a.py ########
aa = "Hello World"
####### b.py ########
from a import aa
print aa #OK
print a.aa #ERROR, there will be error "a" is not defined