new_contents: import sys
  from pprint import pprint
  import argparse
  from expression import *
  from parser import Parser
  
  
  class StackOverflow(Parser):
      cover = XPath('//div[@id="mainbar"]/header/div//img/@src') | Index(0)
      title = XPath('//h1[@class="fs-headline1 mb4"]/a/text()') | Index(0) | F(str.strip)
      company = XPath('//h1[@class="fs-headline1 mb4"]/following-sibling::div/a/text()') | Index(0)
      location = XPath('//h1[@class="fs-headline1 mb4"]/following-sibling::div/a/following-sibling::span/text()') | Join('') | StripNonAlNum()
      description = XPath('//h2[contains(text(), "Job description")]/following-sibling::div//text()') | Join('') | F(str.strip)
  
  
  
  if __name__ == '__main__':
      parser = StackOverflow()
      data = parser.parse(sys.argv[1])
      pprint(data)
  
subject: Add example of parser