<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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))