```lang=python
@pytest.mark.parametrize(
"value", [pytest.param("foo", id="str"), pytest.param(1, id="int")]
)
def test_revision_add_non_bytes_headers(self, swh_storage, value):
extra_headers = [["foo", b"baz"], ["foo", value]]
swh_storage.revision_add(
[{**data.revision, "metadata": {"extra_headers": extra_headers}}]
)
(r,) = swh_storage.revision_get([data.revision["id"]])
assert r["metadata"]["extra_headers"] == extra_headers
```
output:
```
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_api_client.py::TestStorage::test_revision_add_non_bytes_headers[str] PASSED [ 12%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_api_client.py::TestStorage::test_revision_add_non_bytes_headers[int] PASSED [ 25%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_cassandra.py::TestCassandraStorage::test_revision_add_non_bytes_headers[str] FAILED [ 37%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_cassandra.py::TestCassandraStorage::test_revision_add_non_bytes_headers[int] FAILED [ 50%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_in_memory.py::TestStorage::test_revision_add_non_bytes_headers[str] PASSED [ 62%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_in_memory.py::TestStorage::test_revision_add_non_bytes_headers[int] PASSED [ 75%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py::TestStorage::test_revision_add_non_bytes_headers[str] FAILED [ 87%]
.tox/py3/lib/python3.7/site-packages/swh/storage/tests/test_storage.py::TestStorage::test_revision_add_non_bytes_headers[int] FAILED [100%]
```