code: def get_all(self):
          # type: () -> typing.Iterable[typing.Tuple[str, str]]
          
          for name, values in six.iteritems(self._as_list):
              for value in values:
                  yield (name, value)
docs: Returns an iterable of all (name, value) pairs.
  
          If a header has multiple values, multiple pairs will be
          returned with the same name.