I have a sequence of left and right values like:

```
val l: Seq[Either[Error, Data]] = Seq(Left(Error), Right(Data), ...)

```

I want to map all `Right` values and display the error for a `Left`.
I have tried:

```
val data: Seq[Data] = l.flatMap {
  case Right(data) => data
  case Left(err)   => println(err) // doesn't work because println is Unit
}

```

Any way to do this?