print statement outputs integer + <nil>

[RafalSkolasinski]

Hey everyone,

First of all, huge thanks for creating this project. For someone moving from Python to Go this is the first thing I hoped to find!

However, I noticed a small issue when running gophernotes from your docker image gopherdata/gophernotes:latest-ds. Simple fmt.Println(a) behave differently than in visualisation in your readme, see screenshot:

[cosmos72]

The animation in README.md is old and no longer fully accurate.
This behavior is actually intentional - see #179 for a description of the reasons behind it.