title: TclError: couldn't connect to display ":0.0"
body: <p>I am using the following imports</p>
  
  <pre class="lang-py prettyprint-override"><code>import tkinter
  from tkinter import *
  </code></pre>
  
  <p>but having this error in colab....</p>
  
  <pre><code>---------------------------------------------------------------------------
  TclError                                  Traceback (most recent call last)
  &lt;ipython-input-74-80b673e2c2ca&gt; in &lt;module&gt;()
  ----&gt; 1 base = Tk()
  
  /usr/lib/python3.6/tkinter/__init__.py in __init__(self, screenName, baseName, className, useTk, sync, use)
     2021                 baseName = baseName + ext
     2022         interactive = 0
  -&gt; 2023         self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
     2024         if useTk:
     2025             self._loadtk()
  
  TclError: couldn't connect to display ":0.0"
  </code></pre>