Code playground did not support Python2

Answer 1

No, it does not support it. It makes sense because the course offered by Sololearn focuses on Python 3. Similarly (if I remember correctly) after 2020 Python 2 will not have more support.

Answer 2

From this website:
http://python3statement.org/
"...significantly before 2020 many of our projects ... [will only be] fixing bugs, and require Python 3 ... [some projects already have]. [The language itself now only include bugfixes / security] ... For [the reasons at the site] the following projects [list at site] have pledged to drop support for Python 2.7 no later than 2020, coinciding with the Python development team’s timeline for dropping support for Python 2.7."
For people who know 2.x: If you learn Python 3.x well NOW, you could work converting businesses who waited a bit long to move.