Return the cookie "name" for "domain" if found
            If there are mote than one, only the first is returned

def _get_cookie(self, name, domain):
        ''' Return the cookie "name" for "domain" if found
            If there are mote than one, only the first is returned
        '''
        for c in self.session.cookies:
            if c.name==name and c.domain==domain:
                return c
        return None