def slide(self, distance):
        """
        Alter the transform of the current extrusion to slide it
        along its extrude_direction vector

        Parameters
        -----------
        distance: float, distance along self.extrude_direction to move
        """
        distance = float(distance)
        translation = np.eye(4)
        translation[2, 3] = distance
        new_transform = np.dot(self.primitive.transform.copy(),
                               translation.copy())
        self.primitive.transform = new_transform
Alter the transform of the current extrusion to slide it
        along its extrude_direction vector

        Parameters
        -----------
        distance: float, distance along self.extrude_direction to move