func (f LookupFunc) Lookup() (io.ReadCloser, error) {
	return f()
}
Lookup implements Lookup interface.
package file
import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"github.com/gobwas/flagutil/parse"
)
type Syntax interface {
	Unmarshal([]byte) (map[string]interface{}, error)
}
type Lookup interface {
	Lookup() (io.ReadCloser, error)
}
var ErrNoFile = fmt.Errorf("file: no file")
type LookupFunc func() (io.ReadCloser, error)