
City's Happiness

Citizens of GridLand are sending emails to each other all the time. They send everything - what they just ate, a funny picture, questions or thoughts that are bothering them right now. All the citizens are happy because they have such a wonderful network that keeps them connected.
The main goal of the Mayor is to control the city's happiness. The city's happiness is a sum of all citizens' happiness. And the happiness of each citizen is equal to the number of citizens (always including oneself) that one can send emails to.
In the mission you need to find the most important district(s) in the city network from the point of letter exchanging. If several districts have the maximal importance,...
CheckiO Extensions allow you to use local files to solve missions. More info in a blog post.
In order to install CheckiO client you'll need installed Python (version at least 3.8)
Install CheckiO Client first:
pip3 install checkio_client
Configure your tool
checkio --domain=py config --key=
Sync solutions into your local folder
checkio sync
(in beta testing) Launch local server so your browser can use it and sync solution between local file end extension on the fly. (doesn't work for safari)
checkio serv -d
Alternatevly, you can install Chrome extension or FF addon
checkio install-plugin
checkio install-plugin --ff
checkio install-plugin --chromium
Read more here about other functionality that the checkio client provides. Feel free to submit an issue in case of any difficulties.