abstracting over arrays, groups, zarr versions

[d-v-b]

Bringing this up because I'm writing something like this in a separate project:

When writing functions that work equally well for V2 Arrays or V3 arrays (and the same for groups), it would be useful to have a array-like type that doesn't depend on the V2 / V3 Array classes, but works for both. These could be very simple runtime checkable protocols:

from typing import Protocol, runtime_checkable, Generic

@runtime_checkable
class ProtoNode(Protocol):
    attributes: Mapping[str, Any]

@runtime_checkable
class ProtoArray(Protocol):
    shape: tuple[int, ...]

TMembers = TypeVar('TMembers', bound=Mapping[str, object])

@runtime_checkable
class ProtoGroup(Protocol, Generic[TMembers]):
    members: TMembers

This is just a sketch -- these can be made fancier of course, and the names are bad, etc.