Run a router based on a user's initial prompt to determine what category best matches from the given options. If there is no good match, the value "DEFAULT" is returned.

Here's an example:

routes = [
  PromptRoute.new!(%{
    name: "marketing_email",
    description: "Create a marketing focused email",
    chain: marketing_email_chain
  }),
  PromptRoute.new!(%{
    name: "blog_post",
    description: "Create a blog post that will be linked from the company's landing page",
    chain: blog_post_chain
  }),
]

selected_route =
  RoutingChain.new(%{
    llm: ChatOpenAI.new(%{model: "gpt-3.5-turbo", stream: false}),
    input_text: "Let's create a marketing blog post about our new product 'Fuzzy Furries'",
    routes: routes,
    default_route: PromptRoute.new!(%{name: "DEFAULT", chain: fallback_chain})
  })
  |> RoutingChain.evaluate()

# The PromptRoute for the `blog_post` should be returned as the `selected_route`.

The llm is the model used to make the determination of which route is the best match. A smaller, faster LLM may be a great choice for the routing decision, then a more complex LLM may be used for a selected route.

The default_route is required and is used as a fallback if the user's prompt doesn't match any of the specified routes. It may also be used in some fallback error situations as well.