If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
of all symbols in the obarray form the set of permissible completions.
-If @var{collection} is a hash table, then the keys that are strings
-are the possible completions. Other keys are ignored.
+If @var{collection} is a hash table, then the keys that are strings or
+symbols are the possible completions. Other keys are ignored.
You can also use a function as @var{collection}. Then the function is
solely responsible for performing completion; @code{try-completion}