if err := os.WriteFile("impl.go", out, 0660); err != nil {
		log.Fatal(err)
	}
}

const pre = `// Code generated by go run gen.go; DO NOT EDIT.

package imageutil

import (
	"image"
)

// DrawYCbCr draws the YCbCr source image on the RGBA destination image with
// r.Min in dst aligned with sp in src. It reports whether the draw was
// successful. If it returns false, no dst pixels were changed.
//

// Code generated by go run gen.go; DO NOT EDIT.

package imageutil

import (
	"image"
)

// DrawYCbCr draws the YCbCr source image on the RGBA destination image with
// r.Min in dst aligned with sp in src. It reports whether the draw was
// successful. If it returns false, no dst pixels were changed.
//
// This function assumes that r is entirely within dst's bounds and the
// translation of r from dst coordinate space to src coordinate space is