''' Python is an interesting language in that it passes mutable types by reference and immutable types by value. Variables that are assigned a mutable object (lists, user-defined classes) contain a pointer (reference) to that object. Any changes made to the variable are reflected in the original object and all pointers pointing to the object. Variables that contain an immutable-type object can have their value changed, but those changes are not reflected in the original object. ''' ''' Mutable > Since a is mutable, b and c simply contain pointers to a. ''' class a: def __init__(self, n): self.n = n b = a(1) c = b b.n = 2 c.n = 3 print(b.n == c.n) # should return True ''' Immutable > Since int is an immutable type, changing e to 2 would change the value of 1 > itself, which would break everything. e and d contain the value 1, and each > variable can be remapped to contain a different value. ''' d = 1 e = d e = 2 print(d == e) # should return False