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faulty default

Your API is still not right

Although the API lets your users invoke the function in its original form, the
nesting is switched on by default. This behavior is not required by everyone and
some people aren’t at all happy.
Another
version of “nester” has I can’t believe it! My
been released...but its programs were back to running
default behavior might not fine, but now everything is
be what you want. indented. Has this thing
changed again?!?

Funny...it works fine
for me.

Of course, if you have some functionality that really ought to be optional
(that is, not the default), you should adjust your code to make it so. But how?

One solution is to add a third argument which is set to True when the
indenting is required and False otherwise. If you ensure that this argument
is False by default, the original functonality becomes the default behavior
and users of your code have to request the new indenting feature explicitly.

Let’s look at adding this final revision.

66 Chapter 2