lab4 4.3 done
lab4 4.4 done
lab4 4.5 done
lab4 4.6 done
lab4 4.7 done
lab4 4.7 done - faulty
Revert "lab4 4.6 done"

This reverts commit bb9e4db5f2a9f7dee6261c4293f5ef12c09626f5.