diff --git a/docs/tutorials/customize.md b/docs/tutorials/customize.md
index 9f4a02a..57d3ff4 100644
--- a/docs/tutorials/customize.md
+++ b/docs/tutorials/customize.md
@@ -4,23 +4,28 @@
 
 You can crate a schema containing the specified table data with a new token using `new(...)` methods.
 
-```python title="generate_attribute.py"
-from t4_devkit.schema import Attribute
-from t4_devkit.common.serialize import serialize_dataclass
-
-# schema data except of the unique identifier token
-data = {
-    "name": "foo",
-    "description": "this is re-generated attribute."
-}
-
-attr1 = Attribute.new(data)
-
-# Also, it allows us to create a copy of the existing table data with a new token
-serialized = serialize_dataclass(attr1)
-attr2 = Attribute.new(serialized)
-
-assert attr1.token != attr2.token
+```python
+>>> from t4_devkit.schema import Attribute
+>>> from t4_devkit.common.serialize import serialize_dataclass
+>>>
+>>> # schema data except of the unique identifier token
+>>> data = {
+...     "name": "foo",
+...     "description": "this is re-generated attribute."
+... }
+>>>
+>>> attr1 = Attribute.new(data)
+>>>
+>>> # Also, it allows us to create a copy of the existing table data with a new token
+>>> serialized = serialize_dataclass(attr1)
+>>> attr2 = Attribute.new(serialized)
+>>>
+>>> attr1.token != attr2.token
+True
+>>> attr1
+Attribute(token='b08701e5095fbd12a45e7f51b85ffc08', name='foo', description='this is re-generated attribute.')
+>>> attr2
+Attribute(token='f40e605870aa29b1473ca6e65255c45e', name='foo', description='this is re-generated attribute.')
 ```
 
 ## Customize Schema Class
@@ -40,14 +45,14 @@ Now you have the following workspace structure:
 my_package
 ├── src
 │   ├── __init__.py
-│   ├── custom_attribute.py
+│   ├── custom_schema.py
 │   └── main.py
 └── pyproject.toml
 ```
 
-By editing `custom_attribute.py`, you can customize `Attribute` as follows:
+By editing `custom_schema.py`, you can overwrite `Attribute` as follows:
 
-```python title="custom_attribute.py"
+```python title="custom_schema.py"
 from __future__ import annotations
 
 from attrs import define, field
@@ -58,7 +63,7 @@ from t4_devkit.common.io import load_json
 __all__ = ["CustomAttribute"]
 
 
-@define
+@define(slots=False)
 @SCHEMAS.register(SchemaName.ATTRIBUTE, force=True)
 class CustomAttribute(SchemaBase):
     """Custom Attribute class ignoring if there is no `description` field.
@@ -72,7 +77,7 @@ class CustomAttribute(SchemaBase):
     description: str | None = field(default=None)
 ```
 
-Note that `CustomAttribute` should be imported before to instantiate `Tier4` class.
+Note that `CustomAttribute` should be imported before instantiating `Tier4` class.
 Then modify `__init__.py` in order to import it automatically:
 
 ```python title="__init__.py"