title: Facing a problem with python Tkinter calculator application
body: <p>I am a beginner to python I am trying to create a calculator application using Tkinter
  So I have used for loop to create buttons and when I pass <code>lambda:onclick(i)</code> in for loop all the buttons are being assigned only to the last value of my iterable
  This is my code.Please help me</p>
  <pre><code>import tkinter as tk
  root=tk.Tk()
  root.title('Simple Calculator!')
  
  e=tk.Entry(root,width=35,borderwidth=5)
  e.grid(row=0,column=0,columnspan=3,padx=10,pady=10)
  
  def onclick(number):
      curr=e.get()
      e.delete(0,'end')
      e.insert(0,str(curr)+str(number))
  
  def onclick4():
      pass
  def onclick3():
      e.delete(0,'end')
  l=[]
  
  w=0
  for i in range(0,10):
  
      l.append(tk.Button(root,text=str(i),command=lambda:onclick(i),padx=40,pady=30))
      w=w+1
  l.append(tk.Button(root,text='+',command=lambda:onclick('+'),padx=40,pady=30))
  l.append(tk.Button(root,text='clrscr',command=onclick3,padx=40,pady=30))
  
  a=0
  for k in range(1,5):
      for j in range(0,3):
          l[a].grid(row=k,column=j)
          a+=1
  
  l.append(tk.Button(root,text='=',command=onclick4,padx=100,pady=30))    
  l[-1].grid(row=5,column=1)
  
  root.mainloop()
  </code></pre>
  <p>THANK YOU !!</p>