Traceback (most recent call last):
File "./prog.py", line 4, in <module>
File "<string>", line 6, in forward
File "/usr/lib/python3.5/turtle.py", line 3812, in __init__
Turtle._screen = Screen()
File "/usr/lib/python3.5/turtle.py", line 3662, in Screen
Turtle._screen = _Screen()
File "/usr/lib/python3.5/turtle.py", line 3678, in __init__
_Screen._root = self._root = _Root()
File "/usr/lib/python3.5/turtle.py", line 434, in __init__
TK.Tk.__init__(self)
File "/usr/lib/python3.5/tkinter/__init__.py", line 1880, in __init__
self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable