Traceback (most recent call last):
  File "/usr/bin/idle", line 5, in <module>
    main()
  File "/usr/lib/python2.7/idlelib/PyShell.py", line 1537, in main
    root = Tk(className="Idle")
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1764, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk,         sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable