code: def escape(s):
      
      if s is None:
          return ""
      elif hasattr(s, "__html__"):
          return text_type(s.__html__())
  
      if not isinstance(s, string_types):
          s = text_type(s)
  
      return (
          s.replace("&", "&amp;")
          .replace("<", "&lt;")
          .replace(">", "&gt;")
          .replace('"', "&quot;")
      )
docs: Replace special characters "&", "<", ">" and (") to HTML-safe sequences.
  
      There is a special handling for `None` which escapes to an empty string.
  
      .. versionchanged:: 0.9
         `quote` is now implicitly on.
  
      :param s: the string to escape.
      :param quote: ignored.