javascript - Where is the `listen` Function in Node.js Defined -

i'm poking around node.js internals, , came across following method definition

//file: node/lib/net.js socket.prototype.listen = function() {   debug('socket.listen');   var self = this;   self.on('connection', arguments[0]);   listen(self, null, null, null); }; 

within socket object's listen method, there's call (seemingly) global function, named listen.

listen(self, null, null, null); 

where javascript method/function defined? i've scoured javascript files in code-base , can't seem find it.

(there's no specific task i'm trying accomplish here, other tracing node's execution path , trying understand patterns in use deep in system.)

it's defined farther down in net.js. of 0.11.5, it's @ line 1089:

function listen(self, address, port, addresstype, backlog, fd) {   if (!cluster) cluster = require('cluster');        if (cluster.ismaster) {     self._listen2(address, port, addresstype, backlog, fd);     return;   }    // ... }