class_docstr: Exception thrown for an unsuccessful HTTP request.
  
  Attributes:
  
  * ``code`` - HTTP error integer error code, e.g. 404.  Error code 599 is
    used when no HTTP response was received, e.g. for a timeout.
  
  * ``response`` - `HTTPResponse` object, if any.
  
  Note that if ``follow_redirects`` is False, redirects become HTTPErrors,
  and you can look at ``error.response.headers['Location']`` to see the
  destination of the redirect.
class_docstr_tok: ["Exception","thrown","for","an","unsuccessful","HTTP","request",".","Attributes",":","*","``","code","``","-","HTTP","error","integer","error","code",",","e.g",".","404",".","Error","code","599","is","used","when","no","HTTP","response","was","received",",","e.g",".","for","a","timeout",".","*","``","response","``","-","`","HTTPResponse","`","object",",","if","any",".","Note","that","if","``","follow_redirects","``","is","False",",","redirects","become","HTTPErrors",",","and","you","can","look","at","``","error.response.headers","[","'Location","'","]","``","to","see","the","destination","of","the","redirect","."]
code: def __str__(self):
      return "HTTP %d: %s" % (self.code, self.message)
  
imports: from __future__ import absolute_import, division, print_function
  import functools
  import time
  import weakref
  from tornado.concurrent import TracebackFuture
  from tornado.escape import utf8, native_str
  from tornado import httputil, stack_context
  from tornado.ioloop import IOLoop
  from tornado.util import Configurable
label_desc: Use image node_id 2 for calling the HTTPError obj's underlying member method code with example usage: obj.__str__() and returns: unknown