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Have you ever looked at some Python code that included *args and **kwargs and wondered what in the world are these? Python is supposed to be immediately readable to someone either new to programming or someone coming from another programming language. What gives? The *args and **kwargs variables you commonly see are arbitrary positional and optional parameters respectively. They allow for your functions to accept dynamic parameters. Before we go into what they are and how to use them, let's briefly go over Python function parameter types. Python allows for positional and optional arguments for functions. Likely you know that a positional argument is one that is fixed in place like the ones in this example: def do_something(name, age): …show more content…

But, what if a user wants to arbitrarily add 3 or more numbers? In a language like Java, we would have had to use something called an overloaded method (though, in Java 8 you can now use optional parameters!). We would have had to create something similar to: ```python def add_nums(num1, num2): return sum(num1, num2) def add_nums(num1, num2, num3): return sum(num1, num2, num3) and so on ... ``` Instead with *args, we can do this: ```python def add_nums(*args): return sum(args) add_nums(1, 3) add_nums(1, 3, 5) add_nums(1, 3, 5, 7) and so on ... ``` This allows for more flexibility. But, note that *args only allows for positional arguments. For example, we can't do this: ```python def add_nums(*args): return sum(args) add_nums(num1=1, num2=3) ``` We would see an error like this: ``` TypeError: add_nums() got an unexpected keyword argument 'num1' ``` In order to accomodate arbitrary optional parameters, we can use *args' cousin, **kwargs. ```python def get_full_name(**kwargs): full_name = [] for k, v in kwargs.items(): full_name.append(kwargs[k]) return ' '.join(full_name) get_full_name(first_name='Ricky', middle_name='Bobby', last_name='Jones') ``` This of course will return 'Ricky Bobby Jones'. Note that our function did not have to know anything about first_name, middle_name or

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