复制文本fi中的值

Question

我使用一个文本文件来存储tkinter组合框的值。如果用户输入的值不在文件中，我希望添加它。一切正常，但如果用户选择了一个现有值，它也会再次添加到列表中。我相信这是因为我正在返回剥离的值，并用'\n'与值进行比较。任何帮助如何纠正这是非常感谢。你知道吗

from tkinter import *
from tkinter import ttk

regionList = open('regions1.txt','r')

root = Tk()
root.configure()
varRegions = StringVar(root, value='')

class MainWindow(Frame):
    def __init__(self,master = None):
        Frame.__init__(self,master)
        self.master = master
        self.grid()
        self.create_widgets()

    def create_widgets(self):
        """Create Window Layout"""
        Boxfont = ('Arial', 12, 'bold')
        self.blank = Label(self,text='').grid(row=2,column=0)
        self.label = Label(self, font=Boxfont, text="Regions").grid(row=3,column=1)
        self.regcombo = ttk.Combobox(self, font = Boxfont, width = 16, textvariable = varRegions)
        self.regcombo.bind("<Return>", self.regcombo_onEnter)
        self.regcombo.bind('<<ComboboxSelected>>',self.regcombo_onEnter)
        self.regcombo['values'] = regionList.readlines()
        self.regcombo.grid(row=3, column=2,sticky = W)
        self.blank = Label(self,text='').grid(row=4,column=0)

    def regcombo_onEnter(self,event):
        varRegions.set(varRegions.get().lower().strip())
        mytext = varRegions.get().strip()
        vals = self.regcombo.cget('values')
        self.regcombo.select_range(0,END)
        print(mytext)
        if not vals:
            self.regcombo.configure(values = (mytext,))
        elif mytext not in vals:
            with open('regions1.txt','a') as f:
                f.write('\n'+ mytext)
                self.regcombo.configure(values = vals + (mytext,))
                f.close
        return 'break'

app = MainWindow(root)
root.mainloop()