mp_obj_t rt_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
    DEBUG_OP_printf("binary %d %p %p\n", op, lhs, rhs);

    // TODO correctly distinguish inplace operators for mutable objects
    // lookup logic that CPython uses for +=:
    //   check for implemented +=
    //   then check for implemented +
    //   then check for implemented seq.inplace_concat
    //   then check for implemented seq.concat
    //   then fail
    // note that list does not implement + or +=, so that inplace_concat is reached first for +=

    if (MP_OBJ_IS_SMALL_INT(lhs)) {
        mp_small_int_t lhs_val = MP_OBJ_SMALL_INT_VALUE(lhs);
        if (MP_OBJ_IS_SMALL_INT(rhs)) {
            mp_small_int_t rhs_val = MP_OBJ_SMALL_INT_VALUE(rhs);
            switch (op) {
                case RT_BINARY_OP_OR:
                case RT_BINARY_OP_INPLACE_OR: lhs_val |= rhs_val; break;
                case RT_BINARY_OP_XOR:
                case RT_BINARY_OP_INPLACE_XOR: lhs_val ^= rhs_val; break;
                case RT_BINARY_OP_AND:
                case RT_BINARY_OP_INPLACE_AND: lhs_val &= rhs_val; break;
                case RT_BINARY_OP_LSHIFT:
                case RT_BINARY_OP_INPLACE_LSHIFT: lhs_val <<= rhs_val; break;
                case RT_BINARY_OP_RSHIFT:
                case RT_BINARY_OP_INPLACE_RSHIFT: lhs_val >>= rhs_val; break;
                case RT_BINARY_OP_ADD:
                case RT_BINARY_OP_INPLACE_ADD: lhs_val += rhs_val; break;
                case RT_BINARY_OP_SUBTRACT:
                case RT_BINARY_OP_INPLACE_SUBTRACT: lhs_val -= rhs_val; break;
                case RT_BINARY_OP_MULTIPLY:
                case RT_BINARY_OP_INPLACE_MULTIPLY: lhs_val *= rhs_val; break;
                case RT_BINARY_OP_FLOOR_DIVIDE:
                case RT_BINARY_OP_INPLACE_FLOOR_DIVIDE: lhs_val /= rhs_val; break;
    #if MICROPY_ENABLE_FLOAT
                case RT_BINARY_OP_TRUE_DIVIDE:
                case RT_BINARY_OP_INPLACE_TRUE_DIVIDE: return mp_obj_new_float((mp_float_t)lhs_val / (mp_float_t)rhs_val);
    #endif

                // TODO implement modulo as specified by Python
                case RT_BINARY_OP_MODULO:
                case RT_BINARY_OP_INPLACE_MODULO: lhs_val %= rhs_val; break;

                // TODO check for negative power, and overflow
                case RT_BINARY_OP_POWER:
                case RT_BINARY_OP_INPLACE_POWER:
                {
                    int ans = 1;
                    while (rhs_val > 0) {
                        if (rhs_val & 1) {
                            ans *= lhs_val;
                        }
                        lhs_val *= lhs_val;
                        rhs_val /= 2;
                    }
                    lhs_val = ans;
                    break;
                }

                default: assert(0);
            }
            if (fit_small_int(lhs_val)) {
                return MP_OBJ_NEW_SMALL_INT(lhs_val);
            }
        } else if (MP_OBJ_IS_TYPE(rhs, &float_type)) {
            return mp_obj_float_binary_op(op, lhs_val, rhs);
        } else if (MP_OBJ_IS_TYPE(rhs, &complex_type)) {
            return mp_obj_complex_binary_op(op, lhs_val, 0, rhs);
        }
    } else if (MP_OBJ_IS_OBJ(lhs)) {

STATIC mp_obj_t list_index(uint n_args, const mp_obj_t *args) {
    assert(2 <= n_args && n_args <= 4);
    assert(MP_OBJ_IS_TYPE(args[0], &mp_type_list));
    mp_obj_list_t *self = args[0];
    return mp_seq_index_obj(self->items, self->len, n_args, args);
}

mp_obj_t mp_obj_dict_store(mp_obj_t self_in, mp_obj_t key, mp_obj_t value) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_dict));
    mp_obj_dict_t *self = self_in;
    mp_map_lookup(&self->map, key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
    return self_in;
}

STATIC mp_obj_t str_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
    mp_obj_type_t *type = mp_obj_get_type(self_in);
    GET_STR_DATA_LEN(self_in, self_data, self_len);
    if (value == MP_OBJ_SENTINEL) {
        // load
#if MICROPY_PY_BUILTINS_SLICE
        if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
            mp_obj_t ostart, ostop, ostep;
            mp_obj_slice_get(index, &ostart, &ostop, &ostep);
            if (ostep != mp_const_none && ostep != MP_OBJ_NEW_SMALL_INT(1)) {
                nlr_raise(mp_obj_new_exception_msg(&mp_type_NotImplementedError,
                    "only slices with step=1 (aka None) are supported"));
            }

            if (type == &mp_type_bytes) {
                mp_int_t start = 0, stop = self_len;
                if (ostart != mp_const_none) {
                    start = MP_OBJ_SMALL_INT_VALUE(ostart);
                    if (start < 0) {
                        start = self_len + start;
                    }
                }
                if (ostop != mp_const_none) {
                    stop = MP_OBJ_SMALL_INT_VALUE(ostop);
                    if (stop < 0) {
                        stop = self_len + stop;
                    }
                }
                return mp_obj_new_str_of_type(type, self_data + start, stop - start);
            }
            const byte *pstart, *pstop;
            if (ostart != mp_const_none) {
                pstart = str_index_to_ptr(type, self_data, self_len, ostart, true);
            } else {
                pstart = self_data;
            }
            if (ostop != mp_const_none) {
                // pstop will point just after the stop character. This depends on
                // the \0 at the end of the string.
                pstop = str_index_to_ptr(type, self_data, self_len, ostop, true);
            } else {
                pstop = self_data + self_len;
            }
            if (pstop < pstart) {
                return MP_OBJ_NEW_QSTR(MP_QSTR_);
            }
            return mp_obj_new_str_of_type(type, (const byte *)pstart, pstop - pstart);
        }
#endif
        if (type == &mp_type_bytes) {
            uint index_val = mp_get_index(type, self_len, index, false);
            return MP_OBJ_NEW_SMALL_INT(self_data[index_val]);
        }
        const byte *s = str_index_to_ptr(type, self_data, self_len, index, false);
        int len = 1;
        if (UTF8_IS_NONASCII(*s)) {
            // Count the number of 1 bits (after the first)
            for (char mask = 0x40; *s & mask; mask >>= 1) {
                ++len;
            }
        }
        return mp_obj_new_str((const char*)s, len, true); // This will create a one-character string
    } else {
        return MP_OBJ_NULL; // op not supported

STATIC mp_obj_t list_copy(mp_obj_t self_in) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
    mp_obj_list_t *self = self_in;
    return mp_obj_new_list(self->len, self->items);
}

STATIC mp_obj_t set_union(mp_obj_t self_in, mp_obj_t other_in) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_set));
    mp_obj_set_t *self = set_copy(self_in);
    set_update_int(self, other_in);
    return self;
}

mp_map_t *mp_obj_dict_get_map(mp_obj_t self_in) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_dict));
    mp_obj_dict_t *self = self_in;
    return &self->map;
}

STATIC mp_obj_t list_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
    mp_obj_list_t *o = lhs;
    switch (op) {
        case RT_BINARY_OP_SUBSCR:
        {
#if MICROPY_ENABLE_SLICE
            if (MP_OBJ_IS_TYPE(rhs, &slice_type)) {
                machine_uint_t start, stop;
                if (!m_seq_get_fast_slice_indexes(o->len, rhs, &start, &stop)) {
                    assert(0);
                }
                mp_obj_list_t *res = list_new(stop - start);
                m_seq_copy(res->items, o->items + start, res->len, mp_obj_t);
                return res;
            }
#endif
            uint index = mp_get_index(o->base.type, o->len, rhs, false);
            return o->items[index];
        }
        case RT_BINARY_OP_ADD:
        {
            if (!MP_OBJ_IS_TYPE(rhs, &list_type)) {
                return NULL;
            }
            mp_obj_list_t *p = rhs;
            mp_obj_list_t *s = list_new(o->len + p->len);
            m_seq_cat(s->items, o->items, o->len, p->items, p->len, mp_obj_t);
            return s;
        }
        case RT_BINARY_OP_INPLACE_ADD:
        {
            if (!MP_OBJ_IS_TYPE(rhs, &list_type)) {
                return NULL;
            }
            list_extend(lhs, rhs);
            return o;
        }
        case RT_BINARY_OP_MULTIPLY:
        {
            if (!MP_OBJ_IS_SMALL_INT(rhs)) {
                return NULL;
            }
            int n = MP_OBJ_SMALL_INT_VALUE(rhs);
            mp_obj_list_t *s = list_new(o->len * n);
            mp_seq_multiply(o->items, sizeof(*o->items), o->len, n, s->items);
            return s;
        }
        case RT_BINARY_OP_EQUAL:
        case RT_BINARY_OP_LESS:
        case RT_BINARY_OP_LESS_EQUAL:
        case RT_BINARY_OP_MORE:
        case RT_BINARY_OP_MORE_EQUAL:
            return MP_BOOL(list_cmp_helper(op, lhs, rhs));
        case RT_BINARY_OP_NOT_EQUAL:
            return MP_BOOL(!list_cmp_helper(RT_BINARY_OP_EQUAL, lhs, rhs));

        default:
            // op not supported
            return NULL;
    }
}

mp_obj_t mp_obj_dict_store(mp_obj_t self_in, mp_obj_t key, mp_obj_t value) {
    assert(MP_OBJ_IS_TYPE(self_in, &dict_type));
    mp_obj_dict_t *self = self_in;
    mp_map_lookup_helper(&self->map, key, true)->value = value;
    return self_in;
}

STATIC mp_obj_t tuple_count(mp_obj_t self_in, mp_obj_t value) {
    assert(MP_OBJ_IS_TYPE(self_in, &tuple_type));
    mp_obj_tuple_t *self = self_in;
    return mp_seq_count_obj(self->items, self->len, value);
}

mp_float_t mp_obj_float_get(mp_obj_t self_in) {
    assert(MP_OBJ_IS_TYPE(self_in, &float_type));
    mp_obj_float_t *self = self_in;
    return self->value;
}

STATIC mp_obj_t list_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
    if (value == MP_OBJ_NULL) {
        // delete
#if MICROPY_PY_BUILTINS_SLICE
        if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
            mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
            mp_bound_slice_t slice;
            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
                mp_raise_NotImplementedError(NULL);
            }

            mp_int_t len_adj = slice.start - slice.stop;
            //printf("Len adj: %d\n", len_adj);
            assert(len_adj <= 0);
            mp_seq_replace_slice_no_grow(self->items, self->len, slice.start, slice.stop, self->items/*NULL*/, 0, sizeof(*self->items));
            // Clear "freed" elements at the end of list
            mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
            self->len += len_adj;
            return mp_const_none;
        }
#endif
        mp_obj_t args[2] = {self_in, index};
        list_pop(2, args);
        return mp_const_none;
    } else if (value == MP_OBJ_SENTINEL) {
        // load
        mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
#if MICROPY_PY_BUILTINS_SLICE
        if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
            mp_bound_slice_t slice;
            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
                return mp_seq_extract_slice(self->len, self->items, &slice);
            }
            mp_obj_list_t *res = list_new(slice.stop - slice.start);
            mp_seq_copy(res->items, self->items + slice.start, res->len, mp_obj_t);
            return MP_OBJ_FROM_PTR(res);
        }
#endif
        size_t index_val = mp_get_index(self->base.type, self->len, index, false);
        return self->items[index_val];
    } else {
#if MICROPY_PY_BUILTINS_SLICE
        if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
            mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
            size_t value_len; mp_obj_t *value_items;
            mp_obj_get_array(value, &value_len, &value_items);
            mp_bound_slice_t slice_out;
            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice_out)) {
                mp_raise_NotImplementedError(NULL);
            }
            mp_int_t len_adj = value_len - (slice_out.stop - slice_out.start);
            //printf("Len adj: %d\n", len_adj);
            if (len_adj > 0) {
                if (self->len + len_adj > self->alloc) {
                    // TODO: Might optimize memory copies here by checking if block can
                    // be grown inplace or not
                    self->items = m_renew(mp_obj_t, self->items, self->alloc, self->len + len_adj);
                    self->alloc = self->len + len_adj;
                }
                mp_seq_replace_slice_grow_inplace(self->items, self->len,
                    slice_out.start, slice_out.stop, value_items, value_len, len_adj, sizeof(*self->items));
            } else {
                mp_seq_replace_slice_no_grow(self->items, self->len,
                    slice_out.start, slice_out.stop, value_items, value_len, sizeof(*self->items));
                // Clear "freed" elements at the end of list
                mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
                // TODO: apply allocation policy re: alloc_size
            }
            self->len += len_adj;
            return mp_const_none;
        }
#endif
        mp_obj_list_store(self_in, index, value);
        return mp_const_none;
    }
}

void mp_obj_complex_get(mp_obj_t self_in, mp_float_t *real, mp_float_t *imag) {
    assert(MP_OBJ_IS_TYPE(self_in, &complex_type));
    mp_obj_complex_t *self = self_in;
    *real = self->real;
    *imag = self->imag;
}

mp_map_t *mp_obj_module_get_globals(mp_obj_t self_in) {
    assert(MP_OBJ_IS_TYPE(self_in, &module_type));
    mp_obj_module_t *self = self_in;
    return self->globals;
}

STATIC mp_obj_t set_discard(mp_obj_t self_in, mp_obj_t item) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_set));
    mp_obj_set_t *self = self_in;
    mp_set_lookup(&self->set, item, MP_MAP_LOOKUP_REMOVE_IF_FOUND);
    return mp_const_none;
}

STATIC mp_obj_t tuple_index(mp_uint_t n_args, const mp_obj_t *args) {
    assert(MP_OBJ_IS_TYPE(args[0], &mp_type_tuple));
    mp_obj_tuple_t *self = args[0];
    return mp_seq_index_obj(self->items, self->len, n_args, args);
}

STATIC mp_obj_t set_symmetric_difference(mp_obj_t self_in, mp_obj_t other_in) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_set));
    self_in = set_copy(self_in);
    set_symmetric_difference_update(self_in, other_in);
    return self_in;
}

void mp_obj_tuple_get(mp_obj_t self_in, mp_uint_t *len, mp_obj_t **items) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_tuple));
    mp_obj_tuple_t *self = self_in;
    *len = self->len;
    *items = &self->items[0];
}

void mp_obj_set_store(mp_obj_t self_in, mp_obj_t item) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_set));
    mp_obj_set_t *self = self_in;
    mp_set_lookup(&self->set, item, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
}

void mp_obj_tuple_del(mp_obj_t self_in) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_tuple));
    mp_obj_tuple_t *self = self_in;
    m_del_var(mp_obj_tuple_t, mp_obj_t, self->len, self);
}