stripNonRun hist =
    case hs_entry hist of
      HistoryRun _ _ -> hist
      _ -> stripNonRun $ hs_parent hist

{- Truncate a history so that it only runs to a particular epoch number -}
stripNonRun hist =
    case hs_entry hist of
      HistoryRun _ _ -> hist
      _ -> stripNonRun $ hs_parent hist

{- Truncate a history so that it only runs to a particular epoch number -}
stripNonRun hist =
    case hs_entry hist of
      HistoryRun _ _ -> hist
      _ -> stripNonRun $ hs_parent hist

{- Truncate a history so that it only runs to a particular epoch number -}