What does asterisk * mean in Python?

Does * have a special meaning in Python as it does in C? I saw a
function like this in the Python
Cookbook:

def get(self, *a,
            **kw)

Would you please
explain it to me or point out where I can find an answer (Google interprets the * as
wild card character and thus I cannot find a satisfactory answer).

Answer

See href="https://docs.python.org/2.7/reference/compound_stmts.html#function-definitions"
rel="noreferrer">Function Definitions in the Language
Reference.

If the
form *identifier is
present, it is initialized to a
tuple
receiving any excess positional
parameters, defaulting to
the empty
tuple. If the form **identifier
is
present, it is initialized to a new
dictionary receiving any
excess

keyword arguments, defaulting to a new
empty
dictionary.

Also,
see rel="noreferrer">Function
Calls.

Assuming that one knows what
positional and keyword arguments are, here are some
examples:

Example
1:

# Excess keyword
            argument (python 2) example:
def foo(a, b, c, **args):
 print "a =
            %s" % (a,)
 print "b = %s" % (b,)
 print "c = %s" % (c,)

            print args

foo(a="testa", d="excess", c="testc", b="testb",
            k="another_excess")

As
you can see in the above example, we only have parameters a, b,
c in the signature of the foo function. Since
d and k are not present, they are put
into the args dictionary. The output of the program
is:

a = testa
b =
            testb
c = testc
{'k': 'another_excess', 'd':
            'excess'}

Example
2:

# Excess positional
            argument (python 2) example:
def foo(a, b, c, *args):
 print "a =
            %s" % (a,)
 print "b = %s" % (b,)
 print "c = %s" % (c,)

            print args

foo("testa", "testb", "testc", "excess",
            "another_excess")

Here,
since we're testing positional arguments, the excess ones have to be on the end, and
*args packs them into a tuple, so the output of this program
is:

a = testa
b =
            testb
c = testc
('excess',
            'another_excess')

You
can also unpack a dictionary or a tuple into arguments of a
function:

def
            foo(a,b,c,**args):
 print "a=%s" % (a,)
 print "b=%s" %
            (b,)
 print "c=%s" % (c,)
 print "args=%s" %
            (args,)

argdict = dict(a="testa", b="testb", c="testc",
            excessarg="string")
foo(**argdict)

Prints:

a=testa
b=testb
c=testc
args={'excessarg':
            'string'}

And

def
            foo(a,b,c,*args):
 print "a=%s" % (a,)
 print "b=%s" %
            (b,)
 print "c=%s" % (c,)
 print "args=%s" %
            (args,)

argtuple =
            ("testa","testb","testc","excess")
foo(*argtuple)

Prints:

a=testa
b=testb
c=testc
args=('excess',)