Sequences can be explicitly/implicitly unpacked into discrete, ordered units of some type. Unpacking happens automatically using the , (comma). (The syntax is also used for Tuple construction.)

Unpacking works only in instances where the number of variables used exactly matches the number of items in the sequence.

In the below examples parenthesis are not required, and are included for clarity.

The most common application of unpacking is to (shallow) copy items into named variables.

Unpacking a List.

>>> seq = [1, 2, 3]
>>> (a, b, c) = seq  # a=1, b=2, c=3

Unpacking a Tuple.

>>> tup = ('a', 'b')
>>> (x, y) = tup # x='a', y='b'

Unpacking the characters of a String.

>>> (fst, snd, thd) = "abc" # fst='a', snd='b', thd='c'

Swapping objects.

>>> x = 1
>>> y = 2
>>> (x, y) = (y, x) # x=2, y=1