as in <code>'x'</code> or <code>'\n'</code>.
Within the quotes, any character may appear except newline and unescaped single
quote. A single quoted character represents the Unicode value
of the character itself,
while multi-character sequences beginning with a backslash encode
values in various formats.
</p>

<p>
The simplest form represents the single character within the quotes;

    assert not override4 or "x-level4" in response.headers
    assert not override5 or "x-level5" in response.headers


def test_openapi():
    client = TestClient(app)
    with warnings.catch_warnings(record=True) as w:
        warnings.simplefilter("always")
        response = client.get("/openapi.json")
        assert issubclass(w[-1].category, UserWarning)