There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "You can find the following code in the urllib_exceptions.py file."

A block of code is set as follows:

# setup crawler
from scrapy.crawler import CrawlerProcess
crawler = CrawlerProcess(settings)
# define the spider for the crawler
crawler.crawl(MySpider())
# start scrapy
print("STARTING ENGINE")
crawler.start()

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

# setup crawler
from scrapy.crawler import CrawlerProcess
crawler = CrawlerProcess(settings)
# define the spider for the crawler
crawler.crawl(MySpider())
# start scrapy
print("STARTING ENGINE")
crawler.start()

Any command-line input or output is written as follows:

pip install lxml

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Among the available plugins for Firefox, we can highlight the HTTP Header Live add-ons."