# File lib/oauth2/access_token.rb, line 6
    def initialize(client, token, refresh_token=nil, expires_in=nil, params={})
      @client = client
      @token = token.to_s
      @refresh_token = refresh_token.to_s
      @expires_in = (expires_in.nil? || expires_in == '') ? nil : expires_in.to_i
      @expires_at = Time.now + @expires_in if @expires_in
      @params = params
      @token_param = 'oauth_token'
    end