commit 14 test getOrElse
commit 14 implement getOrElse
commit 15 test getOrElse for not existing key
commit 16 refactor getOrElse
commit 17 test remove for existing key
commit 18 implement remove
commit 19 refactor test remove
commit 20 test remove for not existing keys
commit 21 refactor remove method
commit test size method
commit refactor size method
test size method for a not consecutively filled array
test size method for an empty array
Final refactorization