I want to have 2 multiple selection combobox returning/showing the values of the list. My code looks like that:

import tkinter as tk
from tkinter import ttk

class Combo(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)

        menubutton = tk.Menubutton(self, text=nom[k][i], 
                                    indicatoron=True, borderwidth=1, relief="raised")
        menu = tk.Menu(menubutton, tearoff=False)
        menubutton.configure(menu=menu)
        menubutton.pack(padx=10, pady=10)

        self.choices = {}
        for choice in (data[k][i]):
            self.choices[choice] = tk.IntVar(value=0)
            # print(self.choices[choice].get())
            #print(self.choices.get())
            menu.add_checkbutton(label=choice, variable=self.choices[choice], 
                                  onvalue=1, offvalue=0,command=self.show)
    def show(self):
        # global selec
        value = []
        for choice in (data[k][i]):
            value.append(self.choices[choice].get())
        print(value)   
        # selec = value
        return value

root = tk.Tk()

canva = tk.Canvas(root, width = 130,height = 50)
canva.pack(fill = "both", expand = True)

pos = Combo(root)
pos = canva.create_window(125,50,anchor = "nw",window = pos)

i=0 
k = 1

a = Combo(root)
a = canva.create_window(125,50,anchor = "nw",window = a)

k = 2

b = Combo(root)
b = canva.create_window(225,50,anchor = "nw",window = b)

root.mainloop()

A huge part of this code comes from this topic : How do I enable multiple selection of values from a combobox?

For now it works for the second combobox but there is an error on the first:

Traceback (most recent call last):
  File "C:", line 1892, in __call__
    return self.func(*args)
  File "c:dbcreation.py", line 285, in show
    value.append(self.choices[choice].get())
KeyError: 'Manual'