code: function tpl_apply_with_register_helper(Handlebars, template_path, data_obj, dest_file_path) {
  	var rs = fs.createReadStream(template_path, {bufferSize: 11}); 
  	var bufferHelper = new BufferHelper();
  
  	rs.on("data", function (trunk){
  			bufferHelper.concat(trunk);
  	});
  
  	rs.on("end", function () {
  		var source = bufferHelper.toBuffer().toString('utf8');
  		var template = Handlebars.compile(source);
  	
      // log(template);
  		
  		var content = template(data_obj);
  
  		fs.writeFile(dest_file_path, content , function (err) {
  		  if (err) throw err;
  		  log('It\'s saved!');
  		});
  
  	});
  }
docs: Custom with helpers