summary
Everything a reader needs in order to judge the recommendation, in one place.
Assembled rather than left for the caller to compose, because a user who has to know which five methods to call in what order will call one of them and stop. The order is deliberate: what the data are, whether a mixture was worth having, what was recommended, how much the criteria agreed, and what should make you doubt it.
Parameters
held
observations the fit has not seen. When supplied, the share the fit cannot account for is reported, which is the strongest check available without a known truth.