message: Took variant out
diff: #include "BaseContainer.h"
  -#include <variant>
  #include <map>
  #include <utility>
  #include <stdexcept>
  @@ -72,8 +71,6 @@ using StdDataFrame = DataFrame<TS, HeteroVector>;
  template<typename TS>
  using DataFrameView = DataFrame<TS, HeteroView>;
  -using VectorVariant = std::variant<>;
  -
  // ----------------------------------------------------------------------------
  // DS is a data storage container. It must have an interface partly identical
  