PrintFrom GEOG 485 or similar previous experience, you should be familiar with defining simple functions that take a set of input parameters and potentially return some value. When calling such a function from somewhere in your Python code, you have to provide values (or expressions that evaluate to some value) for each of these parameters, and these values are then accessible under the names of the respective parameters in the code that makes up the body of the function.
However, from working with different tool functions provided by arcpy and different functions from the Python standard library, you also already know that functions can also have optional parameters, and you can use the names of such parameters to explicitly provide a value for them when calling the function. In this section, we will show you how to write functions with such keyword arguments and functions that take an arbitrary number of parameters, and we will discuss some more details about passing different kinds of values as parameters to a function.