Just like React addons shallowCompare except it ignores functions.
It's not uncommon to want to bind to a instance function or wrap and action creator. The problem with doing this is that even
if the value props don't change, using a new function will trigger a re-render, making it a bad idea to use shallowCompare in that case.
Additionally, the actual behavior of those functions almost never changes.
See this demo for an example.