BatHashcons.MakeTableSourcemodule HT : BatHashtbl.HashedTypetype of the table
hashcons tab k returns either k, adding it to the table tab as a side effect, or if k is already in the table then it returns the hashed object corresponding to that entry.
iter f tab applies f to every live hashed object in the table tab.
fold f tab x0 folds f across every live hashed object in the table tab, starting with value x0