6.14 Arbitrary Argument Lists

• Sometimes a programmer doesn't know how many arguments a function requires
• A function definition can include a args* parameter that collects optional positional parameters into an arbitrary argument list** tuple.

• Adding a final function parameter of **kwargs creates a dictionary containing "extra" arguments not defined in the function definition
  • kwargs is short for keyword arguments.

args and *kwargs rules:

• The * and characters in *args and kwargs are the important symbols.
  • Using "args" and "kwargs" is standard practice, but any valid identifier is acceptable (like perhaps using *condiments in the sandwich example).
• One or both of args or *kwargs can be used.
• They must come last (and in that order if both are used) in the parameter list, otherwise an error occurs.