public void insertGroup(Group group,int position) throws ObjectAlreadyHasException, IndexOutOfBoundsException {
  assertNotContains(group);
  groups.add(position,group.getName());
}

public void insertGroup ( Group group , int position ) throws ObjectAlreadyHasException , IndexOutOfBoundsException { assertNotContains ( group ) ; groups . add ( position , group . getName ( ) ) ; }
inserts a group at a certain position on this track
