# comparing use of == (value comparison) with is (reference comparison)
# for numbers it is the same thing
>>> a = 7
>>> b = 7
>>> a == b
Out[1]: True
>>> a is b
Out[1]: True

# for strings, which are immutable, it depends on the system you are using :(
# in Eclipse
>>> a = 'abc'
>>> b = 'abc'
>>> a == b
Out[1]: True
>>> a is b
Out[1]: True
>>> b = 'a' + 'b' + 'c'
>>> a is b
Out[1]: True
>>> a = 'aaa'
>>> b = 'a' * 3
>>> a is b
Out[1]: True

# in Cloudcoder
>>> a = 'abc'
>>> b = 'abc'
>>> a == b
Out[1]: True
>>> a is b
Out[1]: True
>>> b = 'a' + 'b' + 'c'
>>> a is b
Out[1]: False
>>> a = 'aaa'
>>> b = 'a' * 3
>>> a is b
Out[1]: False

# for lists, which are mutable, they are two very different things
>>> l = [ 1, 2, 3 ]
>>> l2 = [ 1, 2, 3 ]
>>> l3 = l
>>> l == l2
Out[1]: True
>>> l is l2
Out[1]: False
>>> l is l3
Out[1]: True
>>> l2 is l3
Out[1]: False
>>> l3.append(4)
>>> l
[ 1, 2, 3, 4 ]
>>> l[0] = 0
>>> l3
[ 0, 2, 3, 4 ]