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local garbage removal

When you leave a function, its

variables get thrown away

Each time you call a function, Python creates a new stack frame to
record new variables. But what happens when the function ends?

The computer throws away the File this under G, for “garbage."
function’s stack frame!

Remember: the stack frame is there to
record local variables that belong to the
function. They are not designed to be used elsewhere
in the program, because they are local to the function. The whole reason
for using a stack of variables is to allow a function to create local When a variable's
variables that are invisible to the rest of the program. value CANNOT be

And that’s what’s happened with the password variable. The first
time Python saw it was when it was created in the set_password() seen by some code,
function. That meant the password variable was created on the
set_password() function’s stack frame. When the function ended, it is said to be “out
the stack frame was thrown away and Python completely forgot about
the password variable. When your code then tries later to use the of scope.”
password variable to access Twitter, you’re outta luck, because it can’t
be found anymore...

106 Chapter 3