final case classDefaultGraph[E, N, M](value: M, edges: Iterable[E], nodes: Iterable[N], incoming: Map[N, Iterable[E]], outgoing: Map[N, Iterable[E]]) extends Product with Serializable
case class holding the values of a default graph
the fields are private since we want the type class instance to be used for access
case class holding the values of a default graph
the fields are private since we want the type class instance to be used for access