code: def from_httplib(cls, message, duplicates=('set-cookie',)): # Python 2
          
          ret = cls(message.items())
          # ret now contains only the last header line for each duplicate.
          # Importing with all duplicates would be nice, but this would
          # mean to repeat most of the raw parsing already done, when the
          # message object was created. Extracting only the headers of interest 
          # separately, the cookies, should be faster and requires less
          # extra code.
          for key in duplicates:
              ret.discard(key)
              for val in message.getheaders(key):
                  ret.add(key, val)
              return ret
docs: Read headers from a Python 2 httplib message object.