We looked at a number of considerations to design modules and packages. The parallels between a module and singleton class are deep. When we design a module, the essential questions of the encapsulation of the structure and processing are as relevant as they are for class design.

When we design a package, we need to be skeptical of the need for deeply nested structures. We'll need to use packages when there are varying implementations; we looked at a number of ways to handle this variability. We may also need to define a package to combine a number of modules into a single module-like package. We looked at how __init__.py can import from within the package.