func (d *driver) Open(url string) (source.Driver, error) {
	return nil, errors.New("Open() cannot be called on the httpfs passthrough driver")
}
Open completes the implementetion of source.Driver interface. Other methods
are implemented by the embedded PartialDriver struct.
package httpfs
import (
	"errors"
	"net/http"
	"github.com/golang-migrate/migrate/v4/source"
)
type driver struct {
	PartialDriver
}
func New(fs http.FileSystem, path string) (source.Driver, error) {
	var d driver
	if err := d.Init(fs, path); err != nil {
		return nil, err
	}
	return &d, nil
}