Collectable for error tuple, a good idea?

[dmitrykleymenov]

@windexoriginal

for x < - 1..5, into: {:ok, []}, do: is_ok.(x)

How should this chunk behave? For me(if you implement `Collectable` protocol), the result should be something like:

{:ok, [], {:ok, :v1}, {:error, :reason}, ...}