def add_header(self, _name, _value, **_params):
        parts = []
        for k, v in _params.items():
            if v is None:
                parts.append(k.replace('_', '-'))
            else:
                parts.append(_formatparam(k.replace('_', '-'), v))
        if _value is not None:
            parts.insert(0, _value)
        self._headers.append((_name, SEMISPACE.join(parts)))
Extended header setting.
dataset/ETHPy150Open kleientertainment/ds_mod_tools/pkg/win32/Python27/Lib/email/message.py/Message.add_header