How to Draw a spiral staircase

This video shows us how to draw a spiral staircase in a very simple way. Firstly a horizontal line is drawn and upon that a rectangle is drawn. Then four lines are drawn from the four corners of the rectangle and all this four lines are meeting at the same point on the horizontal line which was drawn previously. Then another rectangle is drawn behind the rectangle intersecting the four lines drawn from the four corners of the rectangle. And at the rare end, numbers of lines are drawn in between the two rectangular lines. Then two circles are drawn on either side of the rare end and the circles are made to intersect the four sides of the rectangle. Then two lines are drawn which are tangent to both these circles and two lines are drawn meeting the centers of these circles. Then four smooth curves are drawn along this center line. Then another line which is parallel to this curve is drawn along the center axis following which another adjacent line is drawn to the curve. Then a number of lines are drawn in between these curved lines which will eventually result in a staircase which are spiral. And it is made darker by giving darker shades. In this way you can draw a spiral staircase.