hosts     = []string{"", "h1", "h2"}
		segs      = []string{"/a", "/b", "/{x}"}
		finalSegs = []string{"/a", "/b", "/{f}", "/{m...}", "/{$}"}
	)

	g := genConcat(
		genChoice(methods),
		genChoice(hosts),
		genStar(3, genChoice(segs)),
		genChoice(finalSegs))
	g(collect)
	return pats
}

// A generator is a function that calls its argument with the strings that it
// generates.
type generator func(collect func(string))