def root_snapshot
      return nil if current_snapshot.nil?

      current = current_snapshot
      current = current.parent while current.parent != nil
      current
    end
def root_snapshot
      return nil if current_snapshot.nil?

      current = current_snapshot
      current = current.parent while current.parent != nil
      current
    end
Returns the root snapshot of this virtual machine. This root snapshot
 can be used to traverse the tree of snapshots.

 @return [Snapshot]