class Person(object):
    count = 0
    __count = 0
    def __init__(self, name):
        self.name = name
        Person.__count+=1
        Person.count += 1
p1 = Person('Bob')
print Person.count
p2 = Person('Alice')
print Person.count
try:
    print Person.__count
except AttributeError:
    print 'attributeerror'