  having to call
  pyplot.clf
  every time. If you want to turn this behavior off, use
  st.pyplot(clear_figure=False)
📣 st.cache no longer checks for input mutations. This is the first change
  of our ongoing effort to simplify the caching system and prepare Streamlit
  for the launch of other caching primitives like Session State!
Version 0.51.0
Release date: November 30, 2019
Highlights:
🐕 You can now tweak the behavior of the file watcher with the config option server.fileWatcherType. Use it to switch between:
auto (default) : Streamlit will attempt to use the watchdog module, and
    falls back to polling if watchdog is not available.
watchdog : Force Streamlit to use the watchdog module.
poll : Force Streamlit to always use polling.
none : Streamlit will not watch files.
Notable bug fixes:
