class_docstr: This class provides a set of methods to read, parse and answer
  questions about a single robots.txt file.
code: def __init__(self, url=""):
      self.entries = []
      self.sitemaps = []
      self.default_entry = None
      self.disallow_all = False
      self.allow_all = False
      self.set_url(url)
      self.last_checked = 0
  
imports: import collections
  import urllib.parse
  import urllib.request
label_desc: Use image node_id 1 to create a new RobotFileParser object  with example: obj = RobotFileParser(url)