PDF拆分、合并通过Python实现GUI图形界面，内有完整代码

这是该程序运行后的GUI，希望合并或者拆分PDF选择对应的按钮，会跳出选择框

代码如下所示：

import PyPDF2
import tkinter as tk
from tkinter import filedialog

def merge_pdfs(pdf_files, output_file):
    merger = PyPDF2.PdfMerger()
    for pdf in pdf_files:
        merger.append(pdf)
    merger.write(output_file)
    merger.close()

def split_pdf(input_file):
    pdf_reader = PyPDF2.PdfReader(input_file)
    for page in range(len(pdf_reader.pages)):
        output = PyPDF2.PdfWriter()
        output.add_page(pdf_reader.pages[page])
        with open(f"output_page_{page + 1}.pdf", "wb") as f:
            output.write(f)

def select_pdf_files():
    files = filedialog.askopenfilenames(filetypes=[("PDF Files", "*.pdf")])
    return list(files)

def sel