We're going to build a Command Line Blog. Our application will be able to store our blog posts, associate them to authors, tag them with topics, and provide a Command Line Interface to them.

• Posts should have a title and content.
• Posts should be stored in-memory.
• Posts should have a word count.
• Posts should have an author.
• Posts should be retrievable from memory.
• Posts should be findable from memory.

• Posts should be saved in text files.
• Posts can be loaded from text files.
• Posts can be browsed and shown.
• Posts can be listed by author.

• Authors should have a name.
• Posts belong to an Author.
• Authors have many posts.
• Categories should have a name.
• Posts should belong to a Category.
• Categories have many posts.
• Authors have many Categories through Posts.