Step $1$ requires creating a class for a $2$D point with constant x and y coordinates. Methods for finding the distance between points and the slope between two points need to be implemented.

Step $2$ involves creating a circle class using instances of the point class. The circle class should have constant fields for its properties like radius, and methods for calculating its area and perimeter.

In step $3,$ a sphere class needs to be developed using instances of the square class. The sphere class should have constant fields for its properties like radius, and methods for calculating its volume and surface area.