diff --git a/.github/workflows/python-app.yml b/.github/workflows/python-app.yml
index 48d1bde..e1ba390 100644
--- a/.github/workflows/python-app.yml
+++ b/.github/workflows/python-app.yml
@@ -30,10 +30,11 @@ jobs:
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
     - name: Test with pytest
       run: |
-        pytest --continue-on-collection-errors
+        git fetch --no-tags --prune --depth=1 origin +refs/heads/*:refs/remotes/origin/*
+        git diff origin/main HEAD --name-only -- practice | xargs dirname | sort | uniq | xargs pytest
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names
         flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
         # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
-        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
\ No newline at end of file
diff --git a/practice/simple-linked-list/simple_linked_list.py b/practice/simple-linked-list/simple_linked_list.py
index cbf120e..cb229ee 100644
--- a/practice/simple-linked-list/simple_linked_list.py
+++ b/practice/simple-linked-list/simple_linked_list.py
@@ -1,33 +1,61 @@
 class Node:
-    def __init__(self, value):
-        pass
+    def __init__(self, value, next_node=None):
+        self._value = value
+        self._next_node = next_node
 
     def value(self):
-        pass
+        return self._value
 
     def next(self):
-        pass
-
-
+        return self._next_node
+    
 class LinkedList:
     def __init__(self, values=[]):
-        pass
+        self._head = None
+        self._length = 0
+        # Initialize in normal order
+        for value in values:
+            self.push(value)
 
     def __len__(self):
-        pass
+        count = 0
+        node = self._head
+        while node:
+            count += 1
+            node = node.next()
+        return count
 
     def head(self):
-        pass
+        if not self._head:
+            raise EmptyListException("The list is empty.")
+        return self._head
 
     def push(self, value):
-        pass
+        new_node = Node(value, self._head)
+        self._head = new_node
+        self._length += 1
 
     def pop(self):
-        pass
+        if self._length == 0:
+            raise EmptyListException("The list is empty.")
+        value = self._head.value()
+        self._head = self._head.next()
+        self._length -= 1
+        return value
 
     def reversed(self):
-        pass
-
-
+        return LinkedList(list(self))
+
+    def __iter__(self):
+        node = self._head
+        while node:
+            yield node.value()
+            node = node.next()
+            
 class EmptyListException(Exception):
+    def __init__(self, message):
+        self.message = message
     pass
+
+
+