javascript - what does (**variable) mean in node.js? -

at https://www.airpair.com/javascript/node-js-tutorial see haven't seen before:

var gzip = zlib.creategzip(); var readstream = fs.createreadstream(**filename); // current file var writestream = fs.createwritestream(**dirname + '/out.gz'); 

what ** mean in ...(**filename); , ...(**dirname ...);? thank you

it's typo in tutorial.

var gzip = zlib.creategzip(); var readstream = fs.createreadstream(__filename); // current file var writestream = fs.createwritestream(__dirname + '/out.gz'); 

they globals in node