old_contents: from __future__ import print_function
  import sys, six
  from w3lib.url import is_url
  
  from scrapy.commands import ScrapyCommand
  from scrapy.http import Request
  from scrapy.exceptions import UsageError
  from scrapy.utils.spider import spidercls_for_request, DefaultSpider
  
  class Command(ScrapyCommand):
  
      requires_project = False
  
      def syntax(self):
          return "[options] <url>"
  
      def short_desc(self):
          return "Fetch a URL using the Scrapy downloader"
  
      def long_desc(self):
          return "Fetch a URL using the Scrapy downloader and print its content " \
              "to stdout. You may want to use --nolog to disable logging"
  
      def add_options(self, parser):
          ScrapyCommand.add_options(self, parser)
          parser.add_option("--spider", dest="spider",
              help="use this spider")
          parser.add_option("--headers", dest="headers", action="store_true", \
              help="print response HTTP headers instead of body")
  
      def _print_headers(self, headers, prefix):
          prefix = prefix.encode()
          for key, values in headers.items():
              for value in values:
                  self._print_bytes(prefix + b' ' + key + b': ' + value)
  
      def _print_response(self, response, opts):
          if opts.headers:
              self._print_headers(response.request.headers, '>')
              print('>')
              self._print_headers(response.headers, '<')
          else:
              self._print_bytes(response.body)
  
      def _print_bytes(self, bytes_):
          bytes_writer = sys.stdout if six.PY2 else sys.stdout.buffer
          bytes_writer.write(bytes_ + b'\n')
  
      def run(self, args, opts):
          if len(args) != 1 or not is_url(args[0]):
              raise UsageError()
          cb = lambda x: self._print_response(x, opts)
          request = Request(args[0], callback=cb, dont_filter=True)
          request.meta['handle_httpstatus_all'] = True
  
          spidercls = DefaultSpider
          spider_loader = self.crawler_process.spider_loader
          if opts.spider:
              spidercls = spider_loader.load(opts.spider)
          else:
              spidercls = spidercls_for_request(spider_loader, request, spidercls)
          self.crawler_process.crawl(spidercls, start_requests=lambda: [request])
          self.crawler_process.start()
  
new_contents: from __future__ import print_function
  import sys, six
  from w3lib.url import is_url
  
  from scrapy.commands import ScrapyCommand
  from scrapy.http import Request
  from scrapy.exceptions import UsageError
  from scrapy.utils.spider import spidercls_for_request, DefaultSpider
  
  class Command(ScrapyCommand):
  
      requires_project = False
  
      def syntax(self):
          return "[options] <url>"
  
      def short_desc(self):
          return "Fetch a URL using the Scrapy downloader"
  
      def long_desc(self):
          return "Fetch a URL using the Scrapy downloader and print its content " \
              "to stdout. You may want to use --nolog to disable logging"
  
      def add_options(self, parser):
          ScrapyCommand.add_options(self, parser)
          parser.add_option("--spider", dest="spider",
              help="use this spider")
          parser.add_option("--headers", dest="headers", action="store_true", \
              help="print response HTTP headers instead of body")
  
      def _print_headers(self, headers, prefix):
          for key, values in headers.items():
              for value in values:
                  self._print_bytes(prefix + b' ' + key + b': ' + value)
  
      def _print_response(self, response, opts):
          if opts.headers:
              self._print_headers(response.request.headers, b'>')
              print('>')
              self._print_headers(response.headers, b'<')
          else:
              self._print_bytes(response.body)
  
      def _print_bytes(self, bytes_):
          bytes_writer = sys.stdout if six.PY2 else sys.stdout.buffer
          bytes_writer.write(bytes_ + b'\n')
  
      def run(self, args, opts):
          if len(args) != 1 or not is_url(args[0]):
              raise UsageError()
          cb = lambda x: self._print_response(x, opts)
          request = Request(args[0], callback=cb, dont_filter=True)
          request.meta['handle_httpstatus_all'] = True
  
          spidercls = DefaultSpider
          spider_loader = self.crawler_process.spider_loader
          if opts.spider:
              spidercls = spider_loader.load(opts.spider)
          else:
              spidercls = spidercls_for_request(spider_loader, request, spidercls)
          self.crawler_process.crawl(spidercls, start_requests=lambda: [request])
          self.crawler_process.start()
  
subject: use byte constants for prefix instead of encoding it