Indent block inside a fn match

Before:

```ex
defp into(stream, device, raw) do
  fn
    :ok, {:cont, x} ->
    case raw do
      true  -> IO.binwrite(device, x)
      false -> IO.write(device, x)
    end
    :ok, _ -> stream
  end
end
```

After:

```ex
defp into(stream, device, raw) do
  fn
    :ok, {:cont, x} ->
      case raw do
        true  -> IO.binwrite(device, x)
        false -> IO.write(device, x)
      end
    :ok, _ -> stream
  end
end
```