@Override
    public @Nullable V put(R key, V value) {
      return StandardTable.this.put(key, columnKey, value);
    }

    @Override
    public @Nullable V get(@Nullable Object key) {
      return StandardTable.this.get(key, columnKey);
    }

    @Override
    public boolean containsKey(@Nullable Object key) {
      return StandardTable.this.contains(key, columnKey);
    }

    @Override

    checkArgument(backingMap.isEmpty());
    checkNotNull(factory);
    // TODO(jlevy): Wrap factory to validate that the supplied maps are empty?
    return new StandardTable<>(backingMap, factory);
  }

  /**
   * Returns a view of a table where each value is transformed by a function. All other properties
   * of the table, such as iteration order, are left intact.
   *