code: def short_str(self):
          
          if self.version is None and self.url is None:
              return ''
          return '%s <%s>' % (self.version, self.url)
docs: Return a string of the form "ver <url>" where ver is the distribution
          version and URL is the distribution Home-Page url, or '' if neither
          can be found.
  
          :return: version and URL
          :rtype: str