return KindPrintf
		} else {
			return KindPrint
		}
	}

	return r.funcs[fn]
}

// isWrapper is a fact indicating that a function is a print or printf wrapper.
type isWrapper struct{ Kind Kind }

func (f *isWrapper) AFact() {}

func (f *isWrapper) String() string {
	switch f.Kind {
	case KindPrintf:
		return "printfWrapper"
	case KindPrint:
		return "printWrapper"

package.

An Analyzer that uses facts must declare their types:

	var Analyzer = &analysis.Analyzer{
		Name:      "printf",
		FactTypes: []analysis.Fact{new(isWrapper)},
		...
	}

	type isWrapper struct{} // => *types.Func f “is a printf wrapper”

The driver program ensures that facts for a pass’s dependencies are
generated before analyzing the package and is responsible for propagating