callable-alists: add type predicate (callable-alist?)
callable-vectors: add type predicate (callable-vector?)
callable-strings: add type predicate (callable-strings?)
callable-lists: add type predicate (callable-list?)
callable-hash-tables: add type predicate (callable-hash-table?)
callable-hash-tables: optional initial object (defaults to empty hash table)
callable-alists: optional initial object (defaults to empty list)