npm install gulp-callbackcopied from http://c2journal.com/2014/07/30/gulp-pipe-callback/
Usage
-----
``
``
var gcallback = require(' gulp-callback ')
gulp.src(' ... ')
.pipe(concat(" ... "))
.pipe(gulp.dest(' ... '))
.pipe(gcallback(function() {
console.log(' here ');
}));