class OAuth2::AccessToken

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