Method update

scrapy/http/headers.py:34–41

(  # type: ignore[override]
        self, seq: Mapping[AnyStr, Any] | Iterable[tuple[AnyStr, Any]]
    )

        super().__init__(seq)

    def update(  # type: ignore[override]
        self, seq: Mapping[AnyStr, Any] | Iterable[tuple[AnyStr, Any]]
    ) -> None:
        seq = seq.items() if isinstance(seq, Mapping) else seq
        iseq: dict[bytes, list[bytes]] = {}
        for k, v in seq:
            iseq.setdefault(self.normkey(k), []).extend(self.normvalue(v))
        super().update(iseq)

    def normkey(self, key: AnyStr) -> bytes:  # type: ignore[override]
        """Normalize key to bytes"""