diff --git a/.gitignore b/.gitignore
index 485dee6..53e4fc8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,162 @@
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+cover/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+.pybuilder/
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+#   For a library or package, you might want to ignore these files since the code is
+#   intended to run in multiple environments; otherwise, check them in:
+# .python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# poetry
+#   Similar to Pipfile.lock, it is generally recommended to include poetry.lock in version control.
+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
+#poetry.lock
+
+# pdm
+#   Similar to Pipfile.lock, it is generally recommended to include pdm.lock in version control.
+#pdm.lock
+#   pdm stores project-wide configurations in .pdm.toml, but it is recommended to not include it
+#   in version control.
+#   https://pdm.fming.dev/#use-with-ide
+.pdm.toml
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/
+
+# PyCharm
+#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+#.idea/
+
 .idea
diff --git a/solid/__pycache__/__init__.cpython-310.pyc b/solid/__pycache__/__init__.cpython-310.pyc
new file mode 100644
index 0000000..ad3477d
Binary files /dev/null and b/solid/__pycache__/__init__.cpython-310.pyc differ
diff --git a/solid/dependency_inversion/__init__.py b/solid/dependency_inversion/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/solid/dependency_inversion/file_reader.py b/solid/dependency_inversion/file_reader.py
new file mode 100644
index 0000000..d440cad
--- /dev/null
+++ b/solid/dependency_inversion/file_reader.py
@@ -0,0 +1,40 @@
+import json
+from pathlib import Path
+
+
+class Reader:
+
+    def read_lines(self) -> list[str]:
+        raise Exception("not yet implemented")
+
+
+class FileReader(Reader):
+
+    def __init__(self, path: Path|str):
+        self._path = Path(path)
+
+    def read(self) -> str:
+        return self._path.read_text('utf-8')
+
+    def read_lines(self) -> list[str]:
+        return [l for l in self.read().split('\n') if l.strip()]
+
+
+class User:
+    def __init__(self, name: str):
+        self.name = name
+
+    @classmethod
+    def from_json(cls, blob) -> 'User' | None:
+        if 'name' not in blob:
+            return
+        return cls(blob['name'])
+
+
+class UserLoader:
+    def __init__(self, reader: Reader):
+        self._file_reader = reader
+
+    def get_users(self) -> list[User]:
+        ret = [User.from_json(json.loads(line)) for line in self._file_reader.read_lines()]
+        return [r for r in ret if r is not None]
diff --git a/solid/interface_segregations/__init__.py b/solid/interface_segregations/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/solid/liskov_substitution/__init__.py b/solid/liskov_substitution/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/solid/liskov_substitution/users.py b/solid/liskov_substitution/users.py
new file mode 100644
index 0000000..a56d869
--- /dev/null
+++ b/solid/liskov_substitution/users.py
@@ -0,0 +1,34 @@
+from datetime import datetime
+
+
+class User:
+    def __init__(self, name: str, password: str):
+        self.name = name
+        self._password = password
+
+    def is_right_password(self, password) -> bool:
+        # ne JAMAIS faire cela
+        return password == self._password
+
+
+class Admin(User):
+    def __init__(self, name: str, password: str, one_time_password: str):
+        super(name, password)
+        self._one_time_password = one_time_password
+
+    def is_right_password(self, password, otp_challange) -> bool:
+        is_otp_valid = self._one_time_password == otp_challange
+        return super().is_right_password(password) and is_otp_valid
+
+
+class LoggedInUser:
+    def __init__(self, user: User, logged_in_time: datetime):
+        self.user = user
+        self.logged_in_time = logged_in_time
+
+
+def loging(user: User, password: str) -> LoggedInUser | None:
+    if not user.is_right_password(password):
+        return None
+
+    return LoggedInUser(user, datetime.utcnow())
\ No newline at end of file
diff --git a/solid/open_close/__init__.py b/solid/open_close/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/solid/open_close/users.py b/solid/open_close/users.py
new file mode 100644
index 0000000..f86ba46
--- /dev/null
+++ b/solid/open_close/users.py
@@ -0,0 +1,45 @@
+import sqlite3
+
+
+class User:
+    def __init__(self, name: str):
+        self.name = name
+
+
+class UserStorage:
+    def __init__(self):
+        self._memory: list[User] = []
+
+    def save(self, user: User) -> None:
+        self._memory.append(user)
+
+    def get(self, name: str) -> User | None:
+        for user in self._memory:
+            if user.name == name:
+                return user
+
+    def get_if_name_starts_by_a(self, name: str) -> User | None:
+        if name.lower().startswith('a'):
+            return self.get(name)
+
+
+class SQliteUserStorage(UserStorage):
+    def __init__(self, conn: sqlite3.Connection):
+        self._conn = conn
+
+    @classmethod
+    def create(cls, url: str) -> 'SQliteUserStorage':
+        conn = sqlite3.connect(url)
+        conn.execute('''CREATE TABLE IF NOT EXISTS users(name TEXT UNIQUE NOT NULL)''')
+        return cls(conn)
+
+    def save(self, user: User) -> None:
+        self._conn.execute(
+            '''INSERT INTO users(name) VALUES (?)''', (user.name, )
+        )
+
+    def get(self, name: str) -> User | None:
+        res = self._conn.execute("""SELECT name FROM users WHERE name = ?""", (name, )).fetchone()
+        if res is None:
+            return None
+        return User(res[0])
diff --git a/solid/open_close/users_test.py b/solid/open_close/users_test.py
new file mode 100644
index 0000000..9acb9b8
--- /dev/null
+++ b/solid/open_close/users_test.py
@@ -0,0 +1,40 @@
+from solid.open_close.users import UserStorage, User, SQliteUserStorage
+
+
+class TestUserStorage:
+    def test_happy_path(self):
+        storage = UserStorage()
+        storage.save(User('Eliotte'))
+        assert storage.get('Eliotte') is not None
+
+    def test_not_found(self):
+        storage = UserStorage()
+        assert storage.get('Eliotte') is None
+
+    def test_get_if_name_starts_by_a(self):
+        storage = UserStorage()
+        storage.save(User('Eliotte'))
+        storage.save(User('Andre'))
+
+        assert storage.get_if_name_starts_by_a('Eliotte') is None
+        assert storage.get_if_name_starts_by_a('Andre') is not None
+
+
+class TestSQliteUserStorage:
+    def test_happy_path(self):
+        storage = SQliteUserStorage.create(":memory:")
+        storage.save(User('Eliotte'))
+        assert storage.get('Eliotte') is not None
+
+    def test_not_found(self):
+        storage = SQliteUserStorage.create(":memory:")
+        assert storage.get('Eliotte') is None
+
+    def test_get_if_name_starts_by_a(self):
+        storage = SQliteUserStorage.create(":memory:")
+        storage.save(User('Eliotte'))
+        storage.save(User('Andre'))
+
+        assert storage.get_if_name_starts_by_a('Eliotte') is None
+        assert storage.get_if_name_starts_by_a('Andre') is not None
+