Implement BUILD_SLICE opcode (2-arg version).

py/vm.c

@@ -410,6 +410,18 @@ bool mp_execute_byte_code_2(const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **
                         sp++;
                         break;
 
+                    case MP_BC_BUILD_SLICE:
+                        DECODE_UINT;
+                        if (unum == 2) {
+                            obj2 = POP();
+                            obj1 = TOP();
+                            SET_TOP(mp_obj_new_slice(obj1, obj2, NULL));
+                        } else {
+                            printf("3-argument slice is not supported\n");
+                            assert(0);
+                        }
+                        break;
+
                     case MP_BC_UNPACK_SEQUENCE:
                         DECODE_UINT;
                         rt_unpack_sequence(sp[0], unum, sp - unum + 1);