code: def is_pull_request(issue):
      """Return True if the given issue is a pull request."""
      return "pull_request_url" in issue
  
imports: import os
  import json
  import urllib
  import re
  import yaml
  from urllib.request import urlopen
  from datetime import datetime, timedelta
  import requests
label_desc: Use image node_id 14 for calling a global function with example usage: is_pull_request(issue) and returns: unknown