Which of the following is the best explanation of a function?

Select one answer, then check.

• A function is a miniature program.
  Correct. The overview describes a function as "a miniature program with its own input, processing, output workflow".
• A function is just an input and an output.
  Not quite. This leaves out processing: a function also does something with its input on the way to its output.
• A function is a mathematical operator.
  Not quite. A function can involve much more than a single mathematical operation, such as printing, reading input, or working with strings.
• A function is a keyword in Python.
  Not quite. def is the keyword used to define a function; the function itself is the reusable chunk of code it creates.

Which of the following is true?

Select one answer, then check.

• Functions do not necessarily work correctly.
  Correct. Writing a function does not mean it works correctly; that's why the chapter covers testing.
• A unit test is created using the def keyword.
  Not quite. def defines a function; a unit test is written with assert_equal.
• You can use a function called check_equal to test your programs.
  Not quite. The `bakery` library's testing function is named assert_equal, not check_equal.
• The bakery library automatically tests your functions for you.
  Not quite. bakery only provides assert_equal; you still have to write the unit tests yourself.

Which of the following is NOT true?

Select one answer, then check.

• Functions can be defined externally in modules.
  This is true, so it's not the answer: the whole point of external functions is that they live in a module you import.
• Functions must be defined or imported before they can be used.
  This is true, so it's not the answer: a function has to exist, by definition or by import, before you can call it.
• Drafter is an example of a library with external functions.
  This is true, so it's not the answer: Drafter is a Python library whose functions you import, as the External Functions section of the reading shows.
• Functions must be defined in the same module that they are used in.
  Correct, this is NOT true. External functions are defined in one module and imported into another, which is exactly why the "External Functions" section exists.