code: def normalize_url(base_url, rel_url):
      
      if not rel_url:
          return None
  
      if not is_absolute_url(rel_url):
          rel_url = rel_url.replace("../", "/")
  
          if (not base_url.endswith("/")) and (not rel_url.startswith("/")):
              return base_url + "/" + rel_url.replace("../", "/")
  
          return base_url + rel_url.replace("../", "/")
  
      return rel_url
docs: Normalize the `url` - from relative, create absolute URL.
  
      Args:
          base_url (str): Domain with ``protocol://`` string
          rel_url (str): Relative or absolute url.
  
      Returns:
          str/None: Normalized URL or None if `url` is blank.