docs: 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)