%task06-1 - Added dir  solution/performance_monitor.rb
%task06-2 - Added function measure, error when function has parameter
%task06-3 - Added loop while function has parameter n=4
%task07-1 - Added solution/hello_friend.rb
%task07-2 - Renamed solution/friend.rb
%task07-3 - Created class Friend
%task07-4 - Created method greeting