--
-- (1) create a coercion that identifies the family instance type and the
-- representation type from Step (1); ie, it is of the form
--- `Co tvs :: F ts :=: R tvs', where `Co' is the name of the coercion,
+-- `Co tvs :: F ts ~ R tvs', where `Co' is the name of the coercion,
-- `F' the family tycon and `R' the (derived) representation tycon,
-- and
-- (2) produce a `TyConParent' value containing the parent and coercion