docs: def dump_header(iterable, allow_token=True):
      """Dump an HTTP header again.  This is the reversal of
      :func:`parse_list_header`, :func:`parse_set_header` and
      :func:`parse_dict_header`.  This also quotes strings that include an
      equals sign unless you pass it as dict of key, value pairs.
  
      >>> dump_header({'foo': 'bar baz'})
      'foo="bar baz"'
      >>> dump_header(('foo', 'bar baz'))
      'foo, "bar baz"'
  
      :param iterable: the iterable or dict of values to quote.
      :param allow_token: if set to `False` tokens as values are disallowed.
                          See :func:`quote_header_value` for more details.
      """
      if isinstance(iterable, dict):
          items = []
          for key, value in iteritems(iterable):
              if value is None:
                  items.append(key)
              else:
                  items.append(
                      "%s=%s" % (key, quote_header_value(value, allow_token=allow_token))
                  )
      else:
          items = [quote_header_value(x, allow_token=allow_token) for x in iterable]
      return ", ".join(items)