diff --git a/.gitea/workflows/build.yaml b/.gitea/workflows/build.yaml
index b05764c..d7ee4fc 100644
--- a/.gitea/workflows/build.yaml
+++ b/.gitea/workflows/build.yaml
@@ -11,13 +11,19 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           cache: 'pip'
+      - name: Create virtualenv
+        run: |
+          python -m venv .venv
+          .venv/bin/pip install -r requirements.txt
+      - name: Run unit tests
+        run: .venv/bin/python -m unittest discover -s tests
       - name: Execute build
+        run: |
+          .venv/bin/python -m build
+      - name: Publish artifacts
         env:
           TWINE_REPOSITORY_URL: ${{ vars.PYPI_REGISTRY_URL }}
           TWINE_USERNAME: ${{ vars.PUBLISHER_USERNAME }}
           TWINE_PASSWORD: ${{ secrets.PUBLISHER_TOKEN }}
         run: |
-          python -m venv .venv
-          .venv/bin/pip install -r requirements.txt
-          .venv/bin/python -m build
-          .venv/bin/python -m twine upload --repository gitea dist/*{.whl,tar.gz}
\ No newline at end of file
+          .venv/bin/python -m twine upload --repository gitea dist/*{.whl,tar.gz}
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..fa09861
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+__pycache__
+.venv
+*.pyc
diff --git a/pyproject.toml b/pyproject.toml
index e120b74..355f502 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pwo"
-version = "0.0.1"
+version = "0.0.2"
 authors = [
   { name="Walter Oggioni", email="oggioni.walter@gmail.com" },
 ]
diff --git a/src/pwo/__init__.py b/src/pwo/__init__.py
new file mode 100644
index 0000000..886de91
--- /dev/null
+++ b/src/pwo/__init__.py
@@ -0,0 +1 @@
+from .private import format_filesize, async_retry, retry, async_test
diff --git a/src/pwo/private.py b/src/pwo/private.py
new file mode 100644
index 0000000..35304d3
--- /dev/null
+++ b/src/pwo/private.py
@@ -0,0 +1,82 @@
+import math
+from enum import Enum, auto
+from typing import Callable
+from time import sleep
+from asyncio import sleep as async_sleep, Runner
+
+_size_uoms = ('B', 'KiB', 'MiB', 'GiB', 'KiB')
+
+
+def format_filesize(size: int) -> str:
+    counter = 0
+    tmp_size = size
+    while tmp_size > 0:
+        tmp_size //= 1024
+        counter += 1
+    counter -= 1
+    return '%.2f ' % (size / math.pow(1024, counter)) + _size_uoms[counter]
+
+
+
+class ExceptionHandlerOutcome(Enum):
+    THROW = auto()
+    CONTINUE = auto()
+
+
+def retry(
+        max_attempts: int = 3,
+        multiplier: float = 2,
+        initial_delay: float = 1.0,
+        exception_handler: Callable[[Exception], ExceptionHandlerOutcome] =
+        lambda _: ExceptionHandlerOutcome.CONTINUE
+):
+    def wrapper(function):
+        def result(*args, **kwargs):
+            attempts = 0
+            delay = initial_delay
+            while True:
+                attempts += 1
+                try:
+                    return function(*args, **kwargs)
+                except Exception as ex:
+                    if attempts < max_attempts and exception_handler(ex) == ExceptionHandlerOutcome.CONTINUE:
+                        sleep(delay)
+                        delay *= multiplier
+                    else:
+                        raise ex
+
+        return result
+
+    return wrapper
+
+
+def async_retry(
+        max_attempts: int = 3,
+        multiplier: float = 2,
+        initial_delay: float = 1.0,
+        exception_handler=lambda _: ExceptionHandlerOutcome.CONTINUE
+):
+    def wrapper(function):
+        async def result(*args, **kwargs):
+            attempts = 0
+            delay = initial_delay
+            while True:
+                attempts += 1
+                try:
+                    return await function(*args, **kwargs)
+                except Exception as ex:
+                    if attempts < max_attempts and exception_handler(ex) == ExceptionHandlerOutcome.CONTINUE:
+                        await async_sleep(delay)
+                        delay *= multiplier
+                    else:
+                        raise ex
+
+        return result
+
+    return wrapper
+
+def async_test(coro):
+    def wrapper(*args, **kwargs):
+        with Runner() as runner:
+            runner.run(coro(*args, **kwargs))
+    return wrapper
\ No newline at end of file
diff --git a/tests/test_private.py b/tests/test_private.py
new file mode 100644
index 0000000..861f37e
--- /dev/null
+++ b/tests/test_private.py
@@ -0,0 +1,74 @@
+import unittest
+
+from src.pwo import retry, async_retry, async_test
+
+
+class PrivateTest(unittest.TestCase):
+    def test_retry_until_success(self):
+        max_attempts = 20
+        attempt = 0
+
+        expected_result = object()
+
+        @retry(max_attempts=max_attempts, initial_delay=0)
+        def foo():
+            nonlocal attempt
+            attempt += 1
+            if attempt < 10:
+                raise Exception()
+            else:
+                return expected_result
+
+        self.assertEqual(expected_result, foo())
+        self.assertEqual(10, attempt)
+
+    def test_retry_until_max_attempt(self):
+        max_attempts = 20
+        attempt = 0
+
+        @retry(max_attempts=max_attempts, initial_delay=0)
+        def bar():
+            nonlocal attempt
+            attempt += 1
+            raise Exception()
+
+        with self.assertRaises(Exception):
+            bar()
+        self.assertEqual(max_attempts, attempt)
+
+    @async_test
+    async def test_async_retry_until_success(self):
+        max_attempts = 20
+        attempt = 0
+
+        expected_result = object()
+
+        @async_retry(max_attempts=max_attempts, initial_delay=0)
+        async def foo():
+            nonlocal attempt
+            attempt += 1
+            if attempt < 10:
+                raise Exception()
+            else:
+                return expected_result
+
+        self.assertEqual(expected_result, await foo())
+        self.assertEqual(10, attempt)
+
+    @async_test
+    async def test_async_retry_until_max_attempt(self):
+        max_attempts = 20
+        attempt = 0
+
+        @async_retry(max_attempts=max_attempts, initial_delay=0)
+        async def bar():
+            nonlocal attempt
+            attempt += 1
+            raise Exception()
+
+        with self.assertRaises(Exception):
+            await bar()
+        self.assertEqual(max_attempts, attempt)
+
+if __name__ == '__main__':
+    unittest.main()