Uncaught ReferenceError: request is not defined

i am working on simple node js module ... a module that, when i give an ID and a request rate, returns a readable stream which emits location data for the corresponding satellite... i am trying to implement by using sub classing ReadableStream

http://nodejs.org/api/stream.html#stream_class_stream_readable

i am using this api

https://api.wheretheiss.at/v1/satellites/25544

providing my code below..

http://jsfiddle.net/omb3rwqn/1/

var request = require('request');
var url = 'https://api.wheretheiss.at/v1/satellites/25544'
var reader = request(url);
readable.on('readable', function() {

    console.log('got %d characters of string data');

})