How to Use KnoxProxy with Scrapy

"""KnoxProxy + Scrapy -- spider with proxy rotation."""
import scrapy

class KnoxSpider(scrapy.Spider):
    name = "knox_demo"
    start_urls = ["https://httpbin.org/ip"]

    custom_settings = {
        "DOWNLOADER_MIDDLEWARES": {
            "scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware": 110,
        },
        "CONCURRENT_REQUESTS": 32,
        "DOWNLOAD_TIMEOUT": 30,
    }

    def start_requests(self):
        for url in self.start_urls:
            yield scrapy.Request(
                url,
                meta={"proxy": "http://USER:PASS@gw.knoxproxy.com:7000"},
                callback=self.parse,
            )

    def parse(self, response):
        yield {"ip": response.json()["origin"], "url": response.url}