python 报错：TypeError: GUI.replace.<locals>.<lambda>() missing 1 required positional argument: 'event'

我想编写一个文本编辑器，但是它在‘替换’工具中出了问题。

def __replace(self, ta, tb, num, root: tk.Toplevel):
    if num == -1:
        a = self.get()
        a = a.replace(ta, tb)
        self.edit(a)
    elif num >= 0:
        pass
    else:
        a = self.get()
        a = a.replace(ta, tb, num)
        self.edit(a)
    root.destroy()

def replace(self):
    root = tk.Toplevel(self.root)
    root.title('替换')
    label = tk.Label(root, text=u'原始内容:')
    label.pack(padx=10,pady=10)
    entry = tk.Entry(root)
    entry.pack(padx=10,pady=10)
    label2 = tk.Label(root, text=u'替换为:')
    label2.pack(padx=10,pady=10)
    entry2 = tk.Entry(root)
    entry2.pack(padx=10,pady=10)
    label3 = tk.Label(root, text='次数（-1为全部替换）')
    label3.pack(padx=10,pady=10)
    entry3=tk.Entry(root)
    entry3.pack(padx=10,pady=10)
    btn=tk.Button(root,text='替换！',command=lambda event: self.__replace(entry.get(),entry2.get(),entry3.get(),root))
    btn.pack(padx=10,pady=10)