diff --git a/examples/nbs/02-TextClassification.ipynb b/examples/nbs/02-TextClassification.ipynb
index f80b4fa..a8f06c1 100644
--- a/examples/nbs/02-TextClassification.ipynb
+++ b/examples/nbs/02-TextClassification.ipynb
@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "markdown",
-   "id": "52697382",
+   "id": "0",
    "metadata": {
     "id": "52697382"
    },
@@ -13,7 +13,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "e130bd40",
+   "id": "1",
    "metadata": {
     "id": "e130bd40"
    },
@@ -28,7 +28,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "592802fe",
+   "id": "2",
    "metadata": {
     "id": "592802fe"
    },
@@ -42,7 +42,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "uTrRNUfn5wg4",
+   "id": "3",
    "metadata": {
     "id": "uTrRNUfn5wg4"
    },
@@ -55,7 +55,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "bf38e2b8",
+   "id": "4",
    "metadata": {
     "id": "bf38e2b8"
    },
@@ -70,7 +70,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "5fc8603f",
+   "id": "5",
    "metadata": {
     "colab": {
      "base_uri": "https://localhost:8080/",
@@ -119,7 +119,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "pXjv4W2hSs20",
+   "id": "6",
    "metadata": {
     "colab": {
      "base_uri": "https://localhost:8080/",
@@ -219,7 +219,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "9f5d0474",
+   "id": "7",
    "metadata": {
     "id": "9f5d0474",
     "pycharm": {
@@ -251,7 +251,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "4a9c19a3",
+   "id": "8",
    "metadata": {
     "colab": {
      "base_uri": "https://localhost:8080/",
@@ -508,7 +508,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "d0b96bd0-3949-4dd5-b6d9-4fa6ac213e30",
+   "id": "9",
    "metadata": {
     "colab": {
      "base_uri": "https://localhost:8080/"
@@ -536,7 +536,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "6a95bc01-4291-49a8-bea7-c76ba64bf42a",
+   "id": "10",
    "metadata": {
     "colab": {
      "base_uri": "https://localhost:8080/",
diff --git a/examples/nbs/04-RayDataset.ipynb b/examples/nbs/04-RayDataset.ipynb
index 4e9714b..b6564c1 100644
--- a/examples/nbs/04-RayDataset.ipynb
+++ b/examples/nbs/04-RayDataset.ipynb
@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "markdown",
-   "id": "9a226830",
+   "id": "0",
    "metadata": {
     "pycharm": {
      "name": "#%% md\n"
@@ -43,7 +43,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "1fffc779",
+   "id": "1",
    "metadata": {
     "pycharm": {
      "name": "#%%\n"
@@ -59,7 +59,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "b94e30dd",
+   "id": "2",
    "metadata": {
     "pycharm": {
      "name": "#%%\n"
@@ -77,7 +77,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "3822e6bb",
+   "id": "3",
    "metadata": {
     "pycharm": {
      "name": "#%%\n"
@@ -96,7 +96,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "c53a4e2f",
+   "id": "4",
    "metadata": {
     "pycharm": {
      "name": "#%%\n"
@@ -110,7 +110,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "31ac27eb",
+   "id": "5",
    "metadata": {
     "pycharm": {
      "name": "#%%\n"
diff --git a/examples/nbs/05-model_fit.ipynb b/examples/nbs/05-model_fit.ipynb
index ef32702..465968e 100644
--- a/examples/nbs/05-model_fit.ipynb
+++ b/examples/nbs/05-model_fit.ipynb
@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "markdown",
-   "id": "eb3a591f",
+   "id": "0",
    "metadata": {},
    "source": [
     "<!--<badge>--><a href=\"https://colab.research.google.com/github/gradsflow/gradsflow/blob/main/examples/nbs/05-model_fit.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/></a><!--</badge>-->"
@@ -11,7 +11,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "62f766aa",
+   "id": "1",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -32,7 +32,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "5794bc62",
+   "id": "2",
    "metadata": {},
    "outputs": [
     {
@@ -61,7 +61,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "fa61d539",
+   "id": "3",
    "metadata": {},
    "outputs": [
     {
@@ -90,7 +90,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "c4be173e",
+   "id": "4",
    "metadata": {},
    "outputs": [
     {
diff --git a/examples/nbs/06-AutoModel_fit.ipynb b/examples/nbs/06-AutoModel_fit.ipynb
index 7244c37..8ce77f8 100644
--- a/examples/nbs/06-AutoModel_fit.ipynb
+++ b/examples/nbs/06-AutoModel_fit.ipynb
@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "markdown",
-   "id": "6f5e7c30",
+   "id": "0",
    "metadata": {},
    "source": [
     "<!--<badge>--><a href=\"https://colab.research.google.com/github/gradsflow/gradsflow/blob/main/examples/nbs/06-AutoModel_fit.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/></a><!--</badge>-->"
@@ -10,7 +10,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "29409c2e",
+   "id": "1",
    "metadata": {},
    "source": [
     "This example shows how to search hyperparameters for a model with Tuner module."
@@ -19,7 +19,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "babe34df",
+   "id": "2",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -32,7 +32,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "b61db9fd",
+   "id": "3",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -43,7 +43,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "52430b02",
+   "id": "4",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -57,7 +57,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "067473d3",
+   "id": "5",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -75,7 +75,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "c46e0094",
+   "id": "6",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -85,7 +85,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "dd8d5d58",
+   "id": "7",
    "metadata": {},
    "source": [
     "## Registering hyperparameters\n",
@@ -99,7 +99,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "f16828b3",
+   "id": "8",
    "metadata": {},
    "outputs": [
     {
@@ -122,7 +122,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "8b4af23b",
+   "id": "9",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -139,7 +139,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "ef6926ed",
+   "id": "10",
    "metadata": {},
    "outputs": [
     {
@@ -364,7 +364,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "85178f72",
+   "id": "11",
    "metadata": {},
    "source": [
     "### The second way to register hyperparameters is to use Tuner module."
@@ -373,7 +373,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "ad2f4f8f",
+   "id": "12",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -388,7 +388,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "3b1f7c70",
+   "id": "13",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -400,7 +400,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "b3dccb5e",
+   "id": "14",
    "metadata": {},
    "outputs": [
     {
diff --git a/gradsflow/data/common.py b/gradsflow/data/common.py
index 0d281a0..477cc25 100644
--- a/gradsflow/data/common.py
+++ b/gradsflow/data/common.py
@@ -1,4 +1,5 @@
 """Provide some common functionalities/utilities for Datasets"""
+
 #  Copyright (c) 2021 GradsFlow. All rights reserved.
 #
 #  Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/gradsflow/data/image.py b/gradsflow/data/image.py
index d19ea69..19df7d4 100644
--- a/gradsflow/data/image.py
+++ b/gradsflow/data/image.py
@@ -1,4 +1,5 @@
 """Data loader for image dataset"""
+
 #  Copyright (c) 2021 GradsFlow. All rights reserved.
 #
 #  Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/gradsflow/models/base.py b/gradsflow/models/base.py
index 1022f0c..de988e3 100644
--- a/gradsflow/models/base.py
+++ b/gradsflow/models/base.py
@@ -92,16 +92,13 @@ def forward(self, x):
         return self.learner(x)
 
     # skipcp: PTC-W0049
-    def backward(self, loss):
-        ...
+    def backward(self, loss): ...
 
     # skipcp: PTC-W0049
-    def eval(self):
-        ...
+    def eval(self): ...
 
     # skipcp: PTC-W0049
-    def train(self):
-        ...
+    def train(self): ...
 
 
 class BaseModel(Base):