requests-全部異常歸類

IOError	RequestException	HTTPError(RequestException)
		UnrewindableBodyError(RequestException)
		RetryError(RequestException)
		ConnectionError(RequestException)	ProxyError(ConnectionError)
			SSLError(ConnectionError)
			ConnectTimeout(ConnectionError, Timeout)
		Timeout(RequestException)	ReadTimeout
		URLRequired(RequestException)
		TooManyRedirects(RequestException)
		MissingSchema(RequestException, ValueError)
		InvalidSchema(RequestException,ValueError)
		InvalidURL(RequestException,ValueError)
		InvalidHeader(RequestException,ValueError)
		ChunkedEncodingError(RequestException)
		StreamConsumedError(RequestException,TypeError)
		ContentDecodingError(RequestException,BaseHTTPError)
	RequestsWarning(Warning)	FileModeWarning(RequestsWarning, DeprecationWarning)

  異常官方文檔：http://www.python-requests.org/en/master/_modules/requests/exceptions/#RequestException