Getting the selected value from combobox in Tkinter

I've figured out what's wrong in the code.

First, as James said the brackets should be removed when binding justamethod to the combobox.

Second, regarding the type error, this is because justamethod is an event handler, so it should take two parameters, self and event, like this,

def justamethod (self, event): 

After making these changes the code is working well.

from tkinter import ttkfrom tkinter import messageboxfrom tkinter import Tkroot = Tk()root.geometry("400x400")#^ width - heghit window :Dcmb = ttk.Combobox(root, width="10", values=("prova","ciao","come","stai"))#cmb = Comboboxclass TableDropDown(ttk.Combobox):    def __init__(self, parent):        self.current_table = tk.StringVar() # create variable for table        ttk.Combobox.__init__(self, parent)#  init widget        self.config(textvariable = self.current_table, state = "readonly", values = ["Customers", "Pets", "Invoices", "Prices"])        self.current(0) # index of values for current table        self.place(x = 50, y = 50, anchor = "w") # place drop down box def checkcmbo():    if cmb.get() == "prova":        messagebox.showinfo("What user choose", "you choose prova")    elif cmb.get() == "ciao":        messagebox.showinfo("What user choose", "you choose ciao")    elif cmb.get() == "come":        messagebox.showinfo("What user choose", "you choose come")    elif cmb.get() == "stai":        messagebox.showinfo("What user choose", "you choose stai")    elif cmb.get() == "":        messagebox.showinfo("nothing to show!", "you have to be choose something")cmb.place(relx="0.1",rely="0.1")btn = ttk.Button(root, text="Get Value",command=checkcmbo)btn.place(relx="0.5",rely="0.1")root.mainloop()