Sets cookie value.

        :param k: Name for cookie value
        :param v: Cookie value
        :param expires: Cookie expiration date
        :param domain: Cookie domain
        :param path: Cookie path
        :param secure: Flag for `https only`
        :type k: str
        :type v: str
        :type expires: datetime.datetime
        :type domain: str
        :type path: str
        :type secure: bool

def cookie(self, k, v, expires=None, domain=None, path='/', secure=False):
        """ Sets cookie value.

        :param k: Name for cookie value
        :param v: Cookie value
        :param expires: Cookie expiration date
        :param domain: Cookie domain
        :param path: Cookie path
        :param secure: Flag for `https only`
        :type k: str
        :type v: str
        :type expires: datetime.datetime
        :type domain: str
        :type path: str
        :type secure: bool
        """
        ls = ['{}={}'.format(k, v)]

        if expires is not None:
            dt = format_date_time(mktime(expires.timetuple()))
            ls.append('expires={}'.format(dt))

        if domain is not None:
            ls.append('domain={}'.format(domain))

        if path is not None:
            ls.append('path={}'.format(path))

        if secure:
            ls.append('secure')

        return self.header('Set-Cookie', '; '.join(ls), False)