Elaborated Request priority value in Scrapy docs

I confirmed in the code: it looks like -priority is used to add the requests to a queuelib PriorityQueue

I tested with this code (n=2 mostly occurred first, followed by n=1 and then n=0):

    from scrapy.spider import Spider
    from random import shuffle
    from scrapy.http import Request

    class TestSpider(Spider):
        name = "test"
        start_urls = [
            'http://www.linkedin.com/company/scrapinghub?n=8',
            'http://www.linkedin.com/company/scrapinghub?n=9'
        ]

        def parse(self, response):
            reqs = [Request(
                'http://www.linkedin.com/company/scrapinghub?n=0',
                dont_filter=True,
                priority = -50,
                callback=self.parse2
            ) for i in range(10)] + [Request(
                'http://www.linkedin.com/company/scrapinghub?n=1',
                dont_filter=True,
                priority = 0,
                callback=self.parse2
            ) for i in range(10)] + [Request(
                'http://www.linkedin.com/company/scrapinghub?n=2',
                dont_filter=True,
                priority = 50,
                callback=self.parse2
            ) for i in range(10)]
            shuffle(reqs)
            return reqs

        def parse2(self, response):
            pass