def METHOD_NAME():
    mapping1 = {
        "http://somewhere.org/schemas/foo-1.0.0": b"foo",
        "http://somewhere.org/schemas/bar-1.0.0": b"bar",
    }
    mapping2 = {
        "http://somewhere.org/schemas/foo-1.0.0": b"duplicate foo",
        "http://somewhere.org/schemas/baz-1.0.0": b"baz",
        "http://somewhere.org/schemas/foz-1.0.0": "foz",
    }
    manager = ResourceManager([mapping1, mapping2])
    assert isinstance(manager, Mapping)
    assert len(manager) == 4
    assert set(manager) == {
        "http://somewhere.org/schemas/foo-1.0.0",
        "http://somewhere.org/schemas/bar-1.0.0",
        "http://somewhere.org/schemas/baz-1.0.0",
        "http://somewhere.org/schemas/foz-1.0.0",
    }
    assert "http://somewhere.org/schemas/foo-1.0.0" in manager
    assert manager["http://somewhere.org/schemas/foo-1.0.0"] == b"foo"
    assert "http://somewhere.org/schemas/bar-1.0.0" in manager
    assert manager["http://somewhere.org/schemas/bar-1.0.0"] == b"bar"
    assert "http://somewhere.org/schemas/baz-1.0.0" in manager
    assert manager["http://somewhere.org/schemas/baz-1.0.0"] == b"baz"
    assert "http://somewhere.org/schemas/foz-1.0.0" in manager
    assert manager["http://somewhere.org/schemas/foz-1.0.0"] == b"foz"
    with pytest.raises(KeyError, match=r"http://somewhere.org/schemas/missing-1.0.0"):
        manager["http://somewhere.org/schemas/missing-1.0.0"]
    # Confirm that the repr string is reasonable:
    assert "len: 4" in repr(manager)