67   struct is_array {  struct
68     static constexpr bool value = false;
72   struct is_array<ndarray<T, pS>> {  struct
73     static constexpr bool value = true;
77   struct is_array<numpy_iexpr<A>> {  struct
78     static constexpr bool value = true;
82   struct is_array<numpy_vexpr<A, F>> {  struct
83     static constexpr bool value = true;
87   struct is_array<numpy_gexpr<A, S...>> {  struct
88     static constexpr bool value = true;
92   struct is_array<numpy_texpr<A>> {  struct
93     static constexpr bool value = true;
97   struct is_array<numpy_texpr_2<A>> {  struct
98     static constexpr bool value = true;
102   struct is_array<numpy_expr<O, Args...>> {  struct
103     static constexpr bool value = true;