Completes 1.9 exercise

Signed-off-by: Irina Chichikova <diva.artim@gmail.com>
Completes 1.10 exercise

Signed-off-by: Irina Chichikova <diva.artim@gmail.com>
Completes 1.11 exercise

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