func FallbackIDFromContext(ctx context.Context) (string, bool) {
	id, ok := ctx.Value(fallbackKey).(string)
	return id, ok
}
FallbackIDFromContext returns the fallback frequency plan ID and whether it's set using WithFallbackID.
package frequencyplans
import "context"
type fallbackKeyType struct{}
var fallbackKey fallbackKeyType
func WithFallbackID(ctx context.Context, id string) context.Context {
	return context.WithValue(ctx, fallbackKey, id)
}