code: function watchFile(filepath) {
  			if (!watchedFiles[filepath]) {
  				// add a new file to watched files
  				var statStructure = null;
  				try {
  					statStructure = fs.statSync(filepath);
  				} catch (e) { // StatSync can throw an error if the file has dissapeared in between
  					return;
  				}
  
  				watchedFiles[filepath] = statStructure;
  				mtimes[filepath] = +watchedFiles[filepath].mtime;
  			}
  		}
docs: Watch a file.