Response objects are derived from dict and map header names (lower case with the trailing colon removed) to header values. In addition to the dict methods a Response object also has:
true
the the response was returned from the cache.
None
if there are no previous respones.
The Response object also populates the header content-location
, that
contains the URI that was ultimately requested. This is useful if
redirects were encountered, you can determine the ultimate URI that
the request was sent to. All Response objects contain this key value,
including previous
responses so you can determine the entire
chain of redirects.