Is Python a

Chapter 15CHAPTER 15Function Basics15In Part III, we looked at basic procedural statements in Python. Here, we’ll move onto explore a set of additional statements that we can use to create functions of ourown.In simple terms, a function is a device that groups a set of statements so they can berun more than once in a program. Functions also can compute a result value and letus specify parameters that serve as function inputs, which may differ each time thecode is run. Coding an operation as a function makes it a generally useful tool, whichwe can use in a variety of contexts.More fundamentally, functions are the alternative to programming by cutting andpasting—rather than having multiple redundant copies of an operation’s code, wecan factor it into a single function. In so doing, we reduce our future work radically:if the operation must be changed later, we only have one copy to update, not many.Functions are the most basic program structure Python provides for maximizing codereuse and minimizing code redundancy. As we’ll see, functions are also a design toolthat lets us split complex systems into manageable parts. Table 15-1 summarizes theprimary function-related tools we’ll study in this part of the book.Table 15-1. Function-related statements and expressionsStatementCallsdef, return, yieldExamplesmyfunc("spam", "eggs", meat=ham)def adder(a, b=1, *c):return a+b+c[0]global def changer( ):global x; x = 'new'lambdaFuncs = [lambda x: x**2, lambda x: x*3]299