from tkinter import *
def Suma():
          sum=int(int(entry.get())+int(entrada2.get())) #en esta parte sale error
          Label(root,text=sum).pack()
def validate(char, entry_value):
          if char in '1234567890.':     #esto es para validar solo numeros escritos aqui
              return True
          else:
              print('invalid: {s}'.format(s = char))
              return False
def validate2(char, entry_value):
          if char in '1234567890.':
               return True
          else:
              print('invalid: {s}'.format(s = char))
              return False
 
root = Tk()
vcmd = (root.register(validate), '%S', '%P')
entry = Entry(root, validate = 'key', validatecommand = vcmd)
entry.pack()
vcmd1 = (root.register(validate2), '%S', '%P')
entrada2 = Entry(root, validate='key',validatecommand =vcmd1).pack()
boton = Button(root,text="+",command= Suma ).pack()
root.mainloop()