actually, can you make this a trait:
```scala
trait ParquetTBase[T] entends Mappable[T] with TypedSink[T] with LocalTap /* get the etsy tap for local mode */ {
  def manifest: Manifest[T] // subclasses do the implicit thing
  // rest of code here
}

case class FixedPathParquetTBaseSource[T](path: String)(implicit override manifest: Manifest[T])
  extends FixedPathSource(path) with ParquetTBase[T]
// follow the above pattern for TimePath/multiple path versions.
```