Question: UML 1 uses the name Collaboration Diagram. UML 2 uses the name Communication Diagram. [In this link you can find the definition and one nice example](http://www.agilemodeling.com/artifacts/communicationDiagram.htm). [Here you can find a nice reference about how to create them](http://www.uml-diagrams.org/communication-diagrams-reference.html).

Unfortunately, I didn't find this diagram in the software I have been using lately: [DIA](http://dia-installer.de/). I think it is not available in [WhiteStarUML](http://sourceforge.net/projects/whitestaruml/) either. There is a tutorial in the help, but I wasn't able to make it work. As WhiteStarUML is a fork of StartUML, maybe it is just not done yet.

![WhiteStarUML Screenshot](https://i.stack.imgur.com/RzWlC.jpg)

*WhiteStarUML Screenshot: there is a folder for Collaboration Diagram but not a file inside to double click it to create it (like the Class Diagrams or UseCase Diagrams)*

What your favourite free tool to create those diagrams?

Answer: 
I had a similar exception `UnknownTimeZoneError: Can not find any timezone configuration` when i tried to run my app inside a docker container with the latest ubuntu images. It turned out that `tzdata` was missing. Installing `tzdata` package fixed it:

```
apt-get install -y tzdata

# Maybe you will need to reconfigure the timezone as well:
ln -fs /usr/share/zoneinfo/Etc/UTC /etc/localtime
dpkg-reconfigure -f noninteractive tzdata

```

(Use `sudo` if you have to)
All solutions didn't work for me in a Spark cluster. But I found the "pendulum" library and it works just fine.

```
import pendulum
timezone = pendulum.timezone('Europe/Saratov')

```