Accepting a variable number of keyword arguments

One of the limitations of the decorator cached_factory that you developed so far is that it only works with functions that accept positional arguments, but not with functions that accept keyword arguments.

Just like Python has the syntax *args to accept a variable number of positional arguments, the syntax **kwargs accepts a variable number of keyword arguments. Again, the important part of the syntax is the double asterisk, **. It is common in Python to talk about **kwargs, but the name of the variable does not have to be kwargs.

When you use **kwargs, Python will collect all keyword arguments into a dictionary:

def print_kwargs(**kwargs):
    print(kwargs)

print_kwargs()
# {}
print_kwargs(a=1, b=2)
# {'a': 1, 'b': 2}
print_kwargs(bananas=True, colour="yellow")
# {'bananas': True, 'colour': 'yellow'}

**kwargs can also come after some other arguments:

def print_kwargs_after(a, b, **kwargs):
    print(a, b, kwargs)

print_kwargs_after(1, 2)
# 1 2 {}
print_kwargs_after(1, 2, bananas=True)
# 1 2 {'bananas': True}
print_kwargs_after(1, 2, bananas=True, colour="yellow")
# 1 2 {'bananas': True, 'colour': 'yellow'}

*args and **kwargs can be combined, too, but before you see that in action, I have a quick challenge to make sure you’re comfortable with **kwargs.

Write a function update_dictionary that accepts a dictionary as a positional argument and then accepts an arbitrary number of keyword arguments. The dictionary must be updated to include all the key/value pairs specified as positional arguments. If you do it correctly, the snippet below should work:

my_dict = {}

update_dictionary(my_dict)  # No kwargs used.
print(my_dict)  # {}

update_dictionary(my_dict, name="Rodrigo")
print(my_dict)  # {'name': 'Rodrigo'}

update_dictionary(my_dict, name="John", surname="Smith")
print(my_dict)  # {'name': 'John', 'surname': 'Smith'}