def authorize_url(params = nil)
      return nil if self.token.nil?

      params = (params || {}).merge(:oauth_token => self.token)
      build_authorize_url(consumer.authorize_url, params)
    end
def authorize_url(params = nil)
      return nil if self.token.nil?

      params = (params || {}).merge(:oauth_token => self.token)
      build_authorize_url(consumer.authorize_url, params)
    end
Generate an authorization URL for user authorization