tcl::unsupported::representation will expose the actual internal type.
> ::tcl::unsupported is a namespace that contains bits and pieces of Tcl that are experimental, not intended for production code, perhaps useful for debugging and introspecting Tcl, and liable to change or removal without warning.
alt Hacker News
> ::tcl::unsupported is a namespace that contains bits and pieces of Tcl that are experimental, not intended for production code, perhaps useful for debugging and introspecting Tcl, and liable to change or removal without warning.