docs: def _move(self, distance):
          """ Moves the turtle by distance in the direction it is facing. 
          If the pen is lowered it will also add to the currently drawn polyline.
          """
          self._position = self._position + self._orient * distance  
          if self.isPenDown(): 
              x = round(self._position.x, 2)
              y = round(self._position.y, 2)
              self._pointsOfPolyline.append(Vector(x, y))