Completes 1.4 exercise

Signed-off-by: Irina Chichikova <diva.artim@gmail.com>
Completes 1.5 exercise

Signed-off-by: Irina Chichikova <diva.artim@gmail.com>
Completes 1.6 exercise

Signed-off-by: Irina Chichikova <diva.artim@gmail.com>