code: def _attach_new(self, records, current, touch=True):
          
          changes = {
              'attached': [],
              'updated': []
          }
  
          for id, attributes in records.items():
              if id not in current:
                  self.attach(id, attributes, touch)
  
                  changes['attached'].append(id)
              elif len(attributes) > 0 and self.update_existing_pivot(id, attributes, touch):
                  changes['updated'].append(id)
  
          return changes
docs: Attach all of the IDs that aren't in the current dict.