Method copy

src/urllib3/_collections.py:433–436

(self)

            self._container[key.lower()] = [key, *val]

    def copy(self) -> Self:
        clone = type(self)()
        clone._copy_from(self)
        return clone

    def iteritems(self) -> typing.Iterator[tuple[str, str]]:
        """Iterate over all header lines, including duplicate ones."""