What do * and ** before a variable name mean in a function signature? [duplicate]

Answer 1

** means named arguments of the functions.

$ cat 2.py
def k(**argv):
    print argv

k(a=10, b = 20)

$ python 2.py
{'a': 10, 'b': 20}

argv is a dictionary that contains all named arguments of the function.

And you can also reverse it. You can use a dictionary as a set of aruments for a function:

def k(a=10, b=20):
  print a
  print b

d={'a':30,'b':40}
k(**d)

would print

30
40