Asterisk in function call

Question

I\'m using itertools.chain to \"flatten\" a list of lists in this fashion:

uniqueCrossTabs = list(itertools.chain(*uniqueCrossTabs))

how is

Answer 1

It splits the sequence into separate arguments for the function call.

>>> def foo(a, b=None, c=None):
...   print a, b, c
... 
>>> foo([1, 2, 3])
[1, 2, 3] None None
>>> foo(*[1, 2, 3])
1 2 3
>>> def bar(*a):
...   print a
... 
>>> bar([1, 2, 3])
([1, 2, 3],)
>>> bar(*[1, 2, 3])
(1, 2, 3)