diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e660f74
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,141 @@
+# Created by .ignore support plugin (hsz.mobi)
+### Python template
+# 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
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow
+__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/
+
diff --git a/flatonacci.py b/flatonacci.py
index 0b04123..d47451c 100644
--- a/flatonacci.py
+++ b/flatonacci.py
@@ -25,4 +25,18 @@
 
 def flatonacci(signature: list, n: int) -> list:
     # happy coding
-    pass
+    assert isinstance(signature, list) and len(signature) == 3, " signature should be a list and has at least 3 numbers"
+    assert (n >= 0)
+
+    if n == 0:
+        return list()
+
+    copy_signature = signature.copy()
+    for _ in range(n - len(signature)):
+        new_element = sum([
+            copy_signature[-x]
+            for x in range(1, 4)
+        ])
+        copy_signature.extend([new_element])
+
+    return copy_signature
diff --git a/test.py b/test.py
new file mode 100644
index 0000000..e4063fc
--- /dev/null
+++ b/test.py
@@ -0,0 +1,38 @@
+import unittest
+from unittest import TestCase
+
+from flatonacci import flatonacci
+
+
+class FlatonacciTest(TestCase):
+
+    def test_flatonacci_returns_empty_list_when_n_is_zero(self):
+        signature = [1, 1, 1]
+        n = 0
+        result = flatonacci(signature=signature, n=n)
+        self.assertListEqual(
+            list1=list(),
+            list2=result,
+        )
+
+    def test_flatonacci_returns_correct_list_when_n_is_8(self):
+        signature = [1, 1, 1]
+        n = 8
+        result = flatonacci(signature=signature, n=n)
+        self.assertListEqual(
+            list1=[1, 1, 1, 3, 5, 9, 17, 31],
+            list2=result,
+        )
+
+    def test_flatonacci_returns_correct_list_when_n_is_9(self):
+        signature = [0, 0, 1]
+        n = 9
+        result = flatonacci(signature=signature, n=n)
+        self.assertListEqual(
+            list1=[0, 0, 1, 1, 2, 4, 7, 13, 24],
+            list2=result,
+        )
+
+
+if __name__ == '__main__':
+    unittest.main()