Fix payload update code in multi send commands

tools/cmd/at/socket_io.go

@@ -5,6 +5,7 @@ package at
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"net"
 	"time"
@@ -13,6 +14,8 @@ import (
 	"kitty/tools/wcswidth"
 )
 
+var _ = fmt.Print
+
 func write_all_to_conn(conn *net.Conn, data []byte) error {
 	for len(data) > 0 {
 		n, err := (*conn).Write(data)