-spec associations() ->
                      [#kura_assoc{name :: atom(),
                                   type :: belongs_to | has_one | has_many | many_to_many,
                                   schema :: module(),
                                   foreign_key :: atom() | undefined,
                                   ref ::
                                       #kura_ref{fields :: [atom()] | undefined,
                                                 target :: module() | undefined,
                                                 target_key :: [atom()] | undefined} |
                                       undefined,
                                   join_through :: binary() | module() | undefined,
                                   join_keys :: {atom() | [atom()], atom() | [atom()]} | undefined,
                                   through :: [atom()] | undefined,
                                   on_delete :: kura_schema:on_delete() | undefined}].

-spec fields() ->
                [#kura_field{name :: atom(),
                             type :: kura_types:kura_type(),
                             column :: binary() | undefined,
                             default :: term(),
                             primary_key :: boolean(),
                             nullable :: boolean(),
                             virtual :: boolean()}].

-spec generate_id() -> binary().

-spec indexes() -> [{[atom()], map()}].

-spec table() -> binary().