Implement tuple addition.
diff --git a/py/obj.h b/py/obj.h
index f372030..43c0ed5 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -398,6 +398,7 @@
// sequence helpers
void mp_seq_multiply(const void *items, uint item_sz, uint len, uint times, void *dest);
bool m_seq_get_fast_slice_indexes(machine_uint_t len, mp_obj_t slice, machine_uint_t *begin, machine_uint_t *end);
-#define m_seq_copy(dest, src, len, item_sz) memcpy(dest, src, len * sizeof(item_sz))
+#define m_seq_copy(dest, src, len, item_t) memcpy(dest, src, len * sizeof(item_t))
+#define m_seq_cat(dest, src1, len1, src2, len2, item_t) { memcpy(dest, src1, len1 * sizeof(item_t)); memcpy(dest + len1, src2, len2 * sizeof(item_t)); }
bool mp_seq_cmp_bytes(int op, const byte *data1, uint len1, const byte *data2, uint len2);
bool mp_seq_cmp_objs(int op, const mp_obj_t *items1, uint len1, const mp_obj_t *items2, uint len2);