def prepare_cookies(self, cookies):
        """Prepares the given HTTP cookie data.

        This function eventually generates a ``Cookie`` header from the
        given cookies using cookielib. Due to cookielib's design, the header
        will not be regenerated if it already exists, meaning this function
        can only be called once for the life of the
        :class:`PreparedRequest <PreparedRequest>` object. Any subsequent calls
        to ``prepare_cookies`` will have no actual effect, unless the "Cookie"
        header is removed beforehand.
        """
        if isinstance(cookies, cookielib.CookieJar):
            self._cookies = cookies
        else:
            self._cookies = cookiejar_from_dict(cookies)

        cookie_header = get_cookie_header(self._cookies, self)
        if cookie_header is not None:
            self.headers['Cookie'] = cookie_header
Prepares the given HTTP cookie data.

        This function eventually generates a ``Cookie`` header from the
        given cookies using cookielib. Due to cookielib's design, the header
        will not be regenerated if it already exists, meaning this function
        can only be called once for the life of the
        :class:`PreparedRequest <PreparedRequest>` object. Any subsequent calls
        to ``prepare_cookies`` will have no actual effect, unless the "Cookie"
        header is removed beforehand.
        
product/gradle-plugin/src/main/python/pip/_vendor/requests/models.py