Consider a SIS gravitational lens with Einstein radius of 1'' located at coordinate origin,
and calculate the images of a circular background source with radius of 0''.2, assuming that
it is located at the following three positions: inside the Einstein ring at (0''.3, 0''.3),
exactly at Einstein ring at (0''.71, 0''.71) and outside the Einstein ring at (1'', 1'').
Discuss the obtained results.