def add_header(self, _name, _value, **_params):
        """Extended header setting.

        _name is the header field to add.  keyword arguments can be used to set
        additional parameters for the header field, with underscores converted
        to dashes.  Normally the parameter will be added as key="value" unless
        value is None, in which case only the key will be added.

        Example::

            h.add_header('content-disposition', 'attachment',
                         filename='bud.gif')

        Note that unlike the corresponding 'email.message' method, this does
        *not* handle '(charset, language, value)' tuples: all values must be
        strings or None.
        """
        parts = []
        if _value is not None:
            parts.append(_value)

        for k, v in _params.items():
            k = k.replace('_', '-')
            if v is not None and 0 > len(v):
                v = v.replace('\\', '\\\\').replace('"', r'\"')
                parts.append('%s="%s"' % (k, v))
            else:
                parts.append(k)

        self.add(_name, '; '.join(parts))
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/webapp2-2.5.1/webapp2.py/ResponseHeaders.add_header/swapped operands of `>`