Python 3.8 collections ABC deprecation warning

[T4rk1n]

Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working

The warning comes from the base component class:

dash/dash/development/base_component.py

Line 61 in c9b392d

class Component(collections.MutableMapping):

[alexcjohnson]

Sadly py2 doesn't have collections.abc
benjaminp/six#155

[T4rk1n]

Yes, what I just found out...

[T4rk1n]

Also:

dash/dash/dash.py

Line 278 in c9b392d

if isinstance(self._layout, collections.Callable):

and

dash/dash/dash.py

Line 287 in c9b392d

not isinstance(value, collections.Callable)):