We have previously reported that Python 2.7 will retire in 2020. As the time node approaches, a large number of Python projects have announced that they will give up support for Python 2.7 by 2020, including pandas, Zulip, IPython, NumPy. and many more.
In fact, almost all major open-source Python packages now support both Python 3.x and Python 2.7, and most have supported both languages for many years. While there are tools and techniques on the market that can effectively maintain compatibility, there is still little friction in the development of many codes, and developers are not planning to maintain this compatibility indefinitely. Seeing that the official is about to stop supporting Python 2, and more and more people are using, teaching, and recommending Python 3, the authors of these Python packages are naturally more inclined to give up Python 2