method string_type_of_ele = function
ME (Element_value v) ->
Some (Odoc_info.string_of_type_expr v.val_type)
| CE (Class_attribute a) ->
Some (Odoc_info.string_of_type_expr a.att_value.val_type)
| CE (Class_method m) ->
Some (Odoc_info.string_of_type_expr m.met_value.val_type)
| _ ->
None