Guido van Rossum's Code Review #0 and Ghost Ship mission update

Hello, sailors of the code-sea,

You remember Guido van Rossum? Yeah, that guy who created Python. He visits CheckiO from time to time to review some players solutions, check out some of his latest reviews:

• Sim0000's elegant solution gets even better with Guido's advice,

• Guido gives advice on the Network Loops task, noting good usage of the defaultdict(set) function,

• Last year's Cake Rows publication get optimized with a little Guido magic.

Arrrr, guess what? Ghost Missions are back!

Tack down the fabled Pirate Ghost Ship Missions with CheckiO. These Ghost Missions are coming back as part of a non-stop CheckiO explosion! You can now compete in these missions on the Codeship Island.

So, those missions are:

	Ghost Detect: Nobody can see other ships after they witness the Ghost Ship, so now you need to write a locator program in the Ghost Detect mission.
	Safe Coasts: Your target is to make a detailed map with defined safe zones based on regional map and the locations where Flying Dutchman typically appears.

Not only you can now complete in the Ghost Detect mission, it's also become a Code Golf mission!