def add(self, name, value):
        norm_name = HTTPHeaders._normalize_name(name)
        self._last_key = norm_name
        if norm_name in self:
            dict.__setitem__(self, norm_name,
                             native_str(self[norm_name]) + ',' +
                             native_str(value))
            self._as_list[norm_name].append(value)
        else:
            self[norm_name] = value
Adds a new value for the given key.
dataset/ETHPy150Open toastdriven/itty/itty.py/HTTPHeaders.add