def link(self, ref: Optional[Union[str, Element]], *, after_link: str = None, use_desc: bool=False,<EOL>add_subset: bool=True) -> str:
obj = self.obj_for(ref) if isinstance(ref, str) else ref<EOL>nl = '<STR_LIT:\n>'<EOL>if isinstance(obj, str) or obj is None or not self.is_secondary_ref(obj.name):<EOL><INDENT>return self.bbin(ref)<EOL><DEDENT>if isinstance(obj, SlotDefinition):<EOL><INDENT>link_name = ((be(obj.domain) + '<STR_LIT:.>') if obj.alias else '<STR_LIT>') + self.aliased_slot_name(obj)<EOL>link_ref = underscore(obj.name)<EOL><DEDENT>else:<EOL><INDENT>link_name = self.obj_name(obj)<EOL>link_ref = link_name<EOL><DEDENT>desc = self.desc_for(obj, use_desc)<EOL>return f'<STR_LIT>'f'<STR_LIT>' +(f'<STR_LIT>' if add_subset and obj.in_subset else '<STR_LIT>') +(f'<STR_LIT>' if after_link else '<STR_LIT>') + (f'<STR_LIT>' if desc else '<STR_LIT>')<EOL>
Create a link to ref if appropriate.

        @param ref: the name or value of a class, slot, type or the name of a built in type.
        @param after_link: Text to put between link and description
        @param use_desc: True means append a description after the link if available
        @param add_subset: True means add any subset information that is available
        @return: