Stuff

Basically it means if you ever had two functions:function twotimestwo() {   return 2*2;}function twotimesfour() {   return 2*4;}you should try to refactor them such that:function twotimestwo() {	return twotimes(2);}function twotimesfour() {	return twotimes(4);}function twotimes($num) {	return 2*$num;}