feat: implement io.WriteCloser

Author: woorui

buffer.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"time"
 )
@@ -45,6 +46,7 @@ func DefaultErrHandler[T any](err error, elements []T) {
 //
 // If both Threshold and FlushInterval are set to zero, Writing is Flushing.
 type Option[T any] struct {
+	io.WriteCloser
 	// Threshold indicates that the buffer is large enough to trigger flushing,
 	// if Threshold is zero, do not judge threshold.
 	Threshold uint32