code: public <T> T set(List<T> list, int index, T obj) {
          return list.set(index, obj);
      }
docs: Set the value at the given index in the given list. If the value is
  properly set, the previous value will be returned.
  
  @param list The list of set in
  @param index The index within the list to set at
  @param obj The object to set in the list
  
  @return The previously set value
  
  @see List#set(int, Object)