diff --git a/.github/workflows/test.yml b/.github/workflows/basic_test.yml
similarity index 95%
rename from .github/workflows/test.yml
rename to .github/workflows/basic_test.yml
index b186a25..3d01193 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/basic_test.yml
@@ -43,5 +43,5 @@ jobs:
           echo "Show what we have here:"
           ls
           python --version
-          python -m pytest ./tests -s
+          python -m pytest ./tests/test_basic_space.py -s
         shell: bash
diff --git a/.github/workflows/super_model_test.yml b/.github/workflows/super_model_test.yml
new file mode 100644
index 0000000..a287964
--- /dev/null
+++ b/.github/workflows/super_model_test.yml
@@ -0,0 +1,32 @@
+name: Run Python Tests for Super Model
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ubuntu-16.04, ubuntu-18.04, ubuntu-20.04, macos-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Test Super Model
+        run: |
+          python -m pip install pytest numpy
+          python -m pip install torch torchvision torchaudio
+          python -m pytest ./tests/test_super_model.py -s
+        shell: bash
diff --git a/lib/layers/__init__.py b/lib/layers/__init__.py
deleted file mode 100644
index f501b80..0000000
--- a/lib/layers/__init__.py
+++ /dev/null
@@ -1,5 +0,0 @@
-from .drop import DropBlock2d, DropPath
-from .mlp import MLP
-from .weight_init import trunc_normal_
-
-from .positional_embedding import PositionalEncoder
diff --git a/lib/spaces/__init__.py b/lib/spaces/__init__.py
index 2c6ce9b..eb422cf 100644
--- a/lib/spaces/__init__.py
+++ b/lib/spaces/__init__.py
@@ -7,6 +7,8 @@
 from .basic_space import Categorical
 from .basic_space import Continuous
 from .basic_space import Integer
+from .basic_space import Space
+from .basic_space import VirtualNode
 from .basic_op import has_categorical
 from .basic_op import has_continuous
 from .basic_op import get_min
diff --git a/lib/spaces/basic_space.py b/lib/spaces/basic_space.py
index 4664f60..2f45de5 100644
--- a/lib/spaces/basic_space.py
+++ b/lib/spaces/basic_space.py
@@ -7,6 +7,7 @@ import math
 import copy
 import random
 import numpy as np
+from collections import OrderedDict
 
 from typing import Optional
 
@@ -44,6 +45,32 @@ class Space(metaclass=abc.ABCMeta):
         return copy.deepcopy(self)
 
 
+class VirtualNode(Space):
+    """For a nested search space, we represent it as a tree structure.
+
+    For example,
+    """
+
+    def __init__(self, id=None, value=None):
+        self._id = id
+        self._value = value
+        self._attributes = OrderedDict()
+
+    def has(self, x):
+        for key, value in self._attributes.items():
+            if isinstance(value, Space) and value.has(x):
+                return True
+        return False
+
+    def __repr__(self):
+        strs = [self.__class__.__name__ + "("]
+        indent = " " * 4
+        for key, value in self._attributes.items():
+            strs.append(indent + strs(value))
+        strs.append(")")
+        return "\n".join(strs)
+
+
 class Categorical(Space):
     """A space contains the categorical values.
     It can be a nested space, which means that the candidate in this space can also be a search space.
diff --git a/lib/trade_models/transformers.py b/lib/trade_models/transformers.py
index ecf8312..fcef99f 100755
--- a/lib/trade_models/transformers.py
+++ b/lib/trade_models/transformers.py
@@ -12,7 +12,7 @@ import torch
 import torch.nn as nn
 import torch.nn.functional as F
 
-import layers as xlayers
+import xlayers
 
 
 DEFAULT_NET_CONFIG = dict(
diff --git a/lib/xlayers/__init__.py b/lib/xlayers/__init__.py
new file mode 100644
index 0000000..063f5ae
--- /dev/null
+++ b/lib/xlayers/__init__.py
@@ -0,0 +1,11 @@
+#####################################################
+# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2019.01 #
+#####################################################
+# This file is expected to be self-contained, expect
+# for importing from spaces to include search space.
+#####################################################
+from .drop import DropBlock2d, DropPath
+from .mlp import MLP
+from .weight_init import trunc_normal_
+
+from .positional_embedding import PositionalEncoder
diff --git a/lib/layers/drop.py b/lib/xlayers/drop.py
similarity index 100%
rename from lib/layers/drop.py
rename to lib/xlayers/drop.py
diff --git a/lib/layers/mlp.py b/lib/xlayers/mlp.py
similarity index 100%
rename from lib/layers/mlp.py
rename to lib/xlayers/mlp.py
diff --git a/lib/layers/positional_embedding.py b/lib/xlayers/positional_embedding.py
similarity index 100%
rename from lib/layers/positional_embedding.py
rename to lib/xlayers/positional_embedding.py
diff --git a/lib/layers/super_core.py b/lib/xlayers/super_core.py
similarity index 100%
rename from lib/layers/super_core.py
rename to lib/xlayers/super_core.py
diff --git a/lib/layers/super_mlp.py b/lib/xlayers/super_mlp.py
similarity index 87%
rename from lib/layers/super_mlp.py
rename to lib/xlayers/super_mlp.py
index 15546c7..c3ed3e7 100644
--- a/lib/layers/super_mlp.py
+++ b/lib/xlayers/super_mlp.py
@@ -1,16 +1,15 @@
 #####################################################
 # Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2021.03 #
 #####################################################
+import torch
 import torch.nn as nn
-from torch.nn.parameter import Parameter
-from torch import Tensor
 
 import math
 from typing import Optional, Union
 
 import spaces
-from layers.super_module import SuperModule
-from layers.super_module import SuperRunType
+from .super_module import SuperModule
+from .super_module import SuperRunMode
 
 IntSpaceType = Union[int, spaces.Integer, spaces.Categorical]
 BoolSpaceType = Union[bool, spaces.Categorical]
@@ -32,11 +31,11 @@ class SuperLinear(SuperModule):
         self._out_features = out_features
         self._bias = bias
 
-        self._super_weight = Parameter(
+        self._super_weight = torch.nn.Parameter(
             torch.Tensor(self.out_features, self.in_features)
         )
-        if bias:
-            self._super_bias = Parameter(torch.Tensor(self.out_features))
+        if self.bias:
+            self._super_bias = torch.nn.Parameter(torch.Tensor(self.out_features))
         else:
             self.register_parameter("_super_bias", None)
         self.reset_parameters()
@@ -53,6 +52,9 @@ class SuperLinear(SuperModule):
     def bias(self):
         return spaces.has_categorical(self._bias, True)
 
+    def abstract_search_space(self):
+        print('-')
+
     def reset_parameters(self) -> None:
         nn.init.kaiming_uniform_(self._super_weight, a=math.sqrt(5))
         if self.bias:
@@ -60,7 +62,7 @@ class SuperLinear(SuperModule):
             bound = 1 / math.sqrt(fan_in)
             nn.init.uniform_(self._super_bias, -bound, bound)
 
-    def forward_raw(self, input: Tensor) -> Tensor:
+    def forward_raw(self, input: torch.Tensor) -> torch.Tensor:
         return F.linear(input, self._super_weight, self._super_bias)
 
     def extra_repr(self) -> str:
diff --git a/lib/layers/super_module.py b/lib/xlayers/super_module.py
similarity index 91%
rename from lib/layers/super_module.py
rename to lib/xlayers/super_module.py
index f382654..cdfab6c 100644
--- a/lib/layers/super_module.py
+++ b/lib/xlayers/super_module.py
@@ -14,12 +14,12 @@ class SuperRunMode(Enum):
     Default = "fullmodel"
 
 
-class SuperModule(abc.ABCMeta, nn.Module):
+class SuperModule(abc.ABC, nn.Module):
     """This class equips the nn.Module class with the ability to apply AutoDL."""
 
     def __init__(self):
         super(SuperModule, self).__init__()
-        self._super_run_type = SuperRunMode.default
+        self._super_run_type = SuperRunMode.Default
 
     @abc.abstractmethod
     def abstract_search_space(self):
diff --git a/lib/layers/weight_init.py b/lib/xlayers/weight_init.py
similarity index 100%
rename from lib/layers/weight_init.py
rename to lib/xlayers/weight_init.py
diff --git a/notebooks/spaces/random-search-mlp.ipynb b/notebooks/spaces/random-search-mlp.ipynb
index a7e676d..18a9324 100644
--- a/notebooks/spaces/random-search-mlp.ipynb
+++ b/notebooks/spaces/random-search-mlp.ipynb
@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 1,
    "metadata": {},
    "outputs": [
     {
@@ -31,29 +31,42 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [
     {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "SuperRunType.FullModel\n",
-      "SuperRunType.FullModel\n",
-      "True\n",
-      "True\n"
+     "ename": "AttributeError",
+     "evalue": "default",
+     "output_type": "error",
+     "traceback": [
+      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+      "\u001b[0;31mAttributeError\u001b[0m                            Traceback (most recent call last)",
+      "\u001b[0;32m~/Desktop/XAutoDL/notebooks/spaces\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      6\u001b[0m \u001b[0mout_features\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mspaces\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mCategorical\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m12\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m24\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m36\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      7\u001b[0m \u001b[0mbias\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mspaces\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mCategorical\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;32mTrue\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;32mFalse\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 8\u001b[0;31m \u001b[0mmodel\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mSuperLinear\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m10\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mout_features\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mbias\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0mbias\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      9\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mmodel\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
+      "\u001b[0;32m~/Desktop/XAutoDL/lib/layers/super_mlp.py\u001b[0m in \u001b[0;36m__init__\u001b[0;34m(self, in_features, out_features, bias)\u001b[0m\n\u001b[1;32m     26\u001b[0m         \u001b[0mbias\u001b[0m\u001b[0;34m:\u001b[0m \u001b[0mBoolSpaceType\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0;32mTrue\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     27\u001b[0m     ) -> None:\n\u001b[0;32m---> 28\u001b[0;31m         \u001b[0msuper\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mSuperLinear\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m__init__\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     29\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     30\u001b[0m         \u001b[0;31m# the raw input args\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
+      "\u001b[0;32m~/Desktop/XAutoDL/lib/layers/super_module.py\u001b[0m in \u001b[0;36m__init__\u001b[0;34m(self)\u001b[0m\n\u001b[1;32m     20\u001b[0m     \u001b[0;32mdef\u001b[0m \u001b[0m__init__\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     21\u001b[0m         \u001b[0msuper\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mSuperModule\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m__init__\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 22\u001b[0;31m         \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_super_run_type\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mSuperRunMode\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mdefault\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     23\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     24\u001b[0m     \u001b[0;34m@\u001b[0m\u001b[0mabc\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mabstractmethod\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
+      "\u001b[0;32m~/anaconda3/lib/python3.8/enum.py\u001b[0m in \u001b[0;36m__getattr__\u001b[0;34m(cls, name)\u001b[0m\n\u001b[1;32m    339\u001b[0m             \u001b[0;32mreturn\u001b[0m \u001b[0mcls\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_member_map_\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mname\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    340\u001b[0m         \u001b[0;32mexcept\u001b[0m \u001b[0mKeyError\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m--> 341\u001b[0;31m             \u001b[0;32mraise\u001b[0m \u001b[0mAttributeError\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mname\u001b[0m\u001b[0;34m)\u001b[0m \u001b[0;32mfrom\u001b[0m \u001b[0;32mNone\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m    342\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    343\u001b[0m     \u001b[0;32mdef\u001b[0m \u001b[0m__getitem__\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mcls\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mname\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
+      "\u001b[0;31mAttributeError\u001b[0m: default"
      ]
     }
    ],
    "source": [
+    "# Test the Linear layer\n",
+    "import spaces\n",
     "from layers.super_core import SuperLinear\n",
     "from layers.super_module import SuperRunMode\n",
     "\n",
-    "print(SuperRunMode.Default)\n",
-    "print(SuperRunMode.FullModel)\n",
-    "print(SuperRunMode.Default == SuperRunMode.FullModel)\n",
-    "print(SuperRunMode.FullModel == SuperRunMode.FullModel)"
+    "out_features = spaces.Categorical(12, 24, 36)\n",
+    "bias = spaces.Categorical(True, False)\n",
+    "model = SuperLinear(10, out_features, bias=bias)\n",
+    "print(model)"
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
   }
  ],
  "metadata": {
diff --git a/tests/test_super_model.py b/tests/test_super_model.py
new file mode 100644
index 0000000..8b6c207
--- /dev/null
+++ b/tests/test_super_model.py
@@ -0,0 +1,28 @@
+#####################################################
+# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2021.03 #
+#####################################################
+# pytest ./tests/test_super_model.py -s             #
+#####################################################
+import sys, random
+import unittest
+import pytest
+from pathlib import Path
+
+lib_dir = (Path(__file__).parent / ".." / "lib").resolve()
+print("library path: {:}".format(lib_dir))
+if str(lib_dir) not in sys.path:
+    sys.path.insert(0, str(lib_dir))
+
+import torch
+from xlayers import super_core
+import spaces
+
+
+class TestSuperLinear(unittest.TestCase):
+    """Test the super linear."""
+
+    def test_super_linear(self):
+        out_features = spaces.Categorical(12, 24, 36)
+        bias = spaces.Categorical(True, False)
+        model = super_core.SuperLinear(10, out_features, bias=bias)
+        print(model)