Как преобразовать принятые данные через Entry из str в int ?

def gold(c):
    b = c/1.618
    a = b/1.618
    gold_counted = "a = " + a + " b = " + b
    return gold_counted
 
label = Label(root, text="Insert length:")
label.pack()
 
entry = Entry(width="25", bd="2")
entry.pack()
length = entry.get()
 
butn = Button(root, text=u"Рассчитать золотое сечение", command=gold(length))
butn.pack()
 
label2 = Label(root, text=gold_counted)
label2.pack()

>>> a = '4.6'
>>> float(a)
4.6

>>> b = '5'
>>> int(b)
5

#! /usr/bin/env python
# -*- coding: utf-8 -*- 
 
from Tkinter import *
 
root=Tk()
root.title("My experiments with GUI")
root.geometry("500x500")
 
gold_counted = "А и Б сидели на трубе"
 
def gold(c):
    b = c/1.618
    a = b/1.618
    gold_counted = "a = " + a + " b = " + b
    return gold_counted
 
def length2():
    length = entry.get() 
    return length
 
label = Label(root, text="Insert length:")
label.pack()
 
entry = Entry(width="25", bd="2")
entry.pack()
entry.focus()
entry.bind("<Return>", length2)
 
length = entry.get()
 
try :
    length = int( entry.get() )
except ValueError:
    label3 = Label(root, text="Bad value")
    label3.pack()
    entry.delete( 0, END )
entry.delete( 0, END )
 
butn = Button(root, text=u"Рассчитать золотое сечение", command=gold(length))
butn.pack()
 
label2 = Label(root, text=gold_counted)
label2.pack()
 
root.mainloop()

from Tkinter import *
 
root = Tk()
root.title("My experiments with GUI")
root.geometry("500x500")
 
gold_counted = "А и Б сидели на трубе"
 
 
def gold(event, c):
    b = c/1.618
    a = b/1.618
    gold_counted = "a = {}, b = {}".format(a, b)
    label2['text'] = gold_counted
 
label = Label(root, text="Insert length:")
label.pack()
 
entry = Entry(width="25", bd="2")
entry.pack()
entry.focus()
 
butn = Button(root, text=u"Рассчитать золотое сечение")
butn.bind("<ButtonRelease-1>", lambda event: gold(event, float(entry.get())))
butn.pack()
 
label2 = Label(root, text=gold_counted)
label2.pack()
 
root.mainloop()

#! /usr/bin/env python
# -*- coding: utf-8 -*-
from Tkinter import *
 
 
class Widgets:
    def __init__(self, root):
        self.create(root)
 
    def create(self, root):
        lab_inf = Label(root, text=u"Впишите длинну:")
        lab_inf.pack()
 
        ent_data = Entry(width="25", bd="2")
        ent_data.pack()
        ent_data.focus()
 
        but_start = Button(root, text=u"Рассчитать золотое сечение")
        but_start.bind("<ButtonRelease-1>", lambda event: gold(event, lab_result, float(ent_data.get())))
        but_start.pack()
 
        lab_result = Label(root, text='А и Б сидели на трубе')
        lab_result.pack()
 
 
def gold(event, place, length):
    b = length / 1.618
    a = b / 1.618
    gold_counted = "a = {}, b = {}".format(a, b)
    place['text'] = gold_counted
 
root = Tk()
root.title("My experiments with GUI")
root.geometry("500x500")
build_widget = Widgets(root)
root.mainloop()