add empty method to array_ref.pxd
+from libcpp cimport bool as bool_t
+
cdef extern from "util/generic/array_ref.h" nogil:
cdef cppclass TArrayRef[T]:
@@ -5,6 +7,7 @@ cdef extern from "util/generic/array_ref.h" nogil:
T& operator[](size_t)
+ bool_t empty()
T* data() except +
size_t size() except +
T* begin() except +
@@ -15,6 +18,7 @@ cdef extern from "util/generic/array_ref.h" nogil:
const T& operator[](size_t)
+ bool_t empty()
const T* data() except +
size_t size() except +
const T* begin() except +
