Should Generators finally be given eltype

[Tamas_Papp]

@yuyichao

But Base.return_type is the building block? It should be the main function needed for that.

No, the building block is an interface for a collection that can

1. either store a new value (eg <: eltype),
2. or allocate a new collection that can.

The caller determines if widening is needed, and calls itself accordingly. Just review “take 2” here, it is really short.