Add DivIcon as accepted type of Marker icon

[pixelsapphire]

A DivIcon works when passed as the icon argument of Marker, but the argument is annotated as Optional[Icon] instead of Optional[Union[Icon, "DivIcon"]].

[Conengmo]

Hi @pixelsapphire, thanks for your PR, that makes sense! Good to improve this.

It's missing an import of that class, can you maybe add that? It will lead to a circular import, so the way to address that is by only importing it for type checking:

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from folium.features import DivIcon

One more thing: I assume this argument also accepts CustomIcon objects. Maybe you can add that as well?

Thanks for your help!

[pixelsapphire]

It's missing an import of that class

My bad, should have checked that first.

I assume this argument also accepts CustomIcon objects. Maybe you can add that as well?

Done and dusted.

[hansthen]

@Conengmo Do you know what is the issue with the failing mypy checks? It seems mypy is bothered by some method signature redefinitions between Branca and Folium.

[pixelsapphire]

@hansthen This is something I've been wondering about too. Why does the render method in Folium classes return None, when this method in Branca classes (as in the Element class itself) returns str?