如何在 Combobox Tkinter 中获取用户选择的值？

我想继续使用用户指定的值。例如，有一个字典，其中的键是用户在中选择的内容combo1：

dct = {'Морковь': ['M1', 'M2', 'M3', 'M4'], 'Лук': ['Л2', 'Л4', 'Л5'], 'Картофель': ['К1', 'К2', 'К7']}

def selected(event):
    # получаем выделенный элемент
    global selection
    selection = combo.get()

root = Tk()
root.geometry('600x300')

combo1 = Combobox(root)
combo1['values'] = tuple(dct.keys())  
combo1.grid(column=0, row=0)
combo1.bind("<<ComboboxSelected>>", selected)

我想创建第二个小部件combo2，用户将在其中通过按键选择我需要的列表。那些。例如，用户选择“Bow”，然后打开一个窗口，其中包含以下元素的选择：“L2”、“L4”、“L5”。但我不明白如何对第二个小部件进行动态更改。我的代码如下所示：

from tkinter import *
from tkinter.ttk import Combobox

def selected(event):
    # получаем выделенный элемент
    global selection1
    selection1 = dct[str(combo1.get())]

def selected2(event):
    # получаем выделенный элемент
    global selection2
    selection2 = combo2.get()  

root = Tk()
root.geometry('600x300')

dct = {'Морковь': ['M1', 'M2', 'M3', 'M4'], 'Лук': ['Л2', 'Л4', 'Л5'], 'Картофель': ['К1', 'К2', 'К7']}
selection1 = None
selection2 = None

combo1 = Combobox(root)
combo1['values'] = tuple(dct.keys())  
combo1.grid(column=0, row=0)
combo1.bind("<<ComboboxSelected>>", selected)

combo2 = Combobox(root)
combo2['values'] = selection1  
combo2.grid(column=0, row=1)
combo2.bind("<<ComboboxSelected>>", selected2)

mainloop()