title: importing pyautogui in ubuntu throwing KEYERROR :DISPLAY
body: <pre><code>Traceback (most recent call last):
    File "1.py", line 1, in &lt;module&gt;
      import pyautogui
    File "/home/prasoon/.local/lib/python2.7/site-packages/pyautogui/__init__.py", line 115, in &lt;module&gt;
      from . import _pyautogui_x11 as platformModule
    File "/home/prasoon/.local/lib/python2.7/site-packages/pyautogui/_pyautogui_x11.py", line 160, in &lt;module&gt;
      _display = Display(os.environ['DISPLAY'])
    File "/usr/lib/python2.7/UserDict.py", line 40, in __getitem__
      raise KeyError(key)
  KeyError: 'DISPLAY'
  </code></pre>
  
  <p>Python version- Python 2.7.15rc1</p>
  
  <p>While running "import pyautogui" this error is being thrown</p>
  
  <p>I run the following commands -</p>
  
  <pre><code>pip install `python3-xlib`
  
  sudo apt-get install scrot
  
  sudo apt-get install python3-tk
  
  sudo apt-get install python3-dev
  
  pip install pyautogui
  </code></pre>