Calling Service Side Script function from another Service Side Script

Create a script include something like this:
name of the script include is : NeedItUtils

isDatePast: function(strDate){
  // Create GlideDateTime objects for the current date and the passed in date
  var rightnow = new GlideDateTime();
  var testdate = new GlideDateTime(strDate);

  // If the testdate is before rightnow, return true, else return false
  if (testdate.before(rightnow)) {
   return true;
  }
  else {
   return false;
  }
 },

Calling this from another business rules something like this below:

// Instantiate the NeedItUtils class.  Call the isDatePast method and pass 
 // the u_when_needed value.
 var niutils = new NeedItUtils();
 var isPast = niutils.isDatePast(current.u_when_needed);

 // If the isDatePast method returns true, the date is in the past.
 if(isPast == true){
  gs.addErrorMessage("When needed date cannot be in the past.  Your request has not been saved to the database.");
  current.setAbortAction(true);
 }