code: @SuppressWarnings("unchecked")
      public <T> Tuple<T> getTuple(TypeTag tag) {
          return cache.get(tag);
      }
docs: Returns a {@link Tuple} of prefabricated values for the specified type.
  
  What happens when there is no value, is undefined. Always call
  {@link #contains(TypeTag)} first.
  
  @param tag A description of the type. Takes generics into account.