cument redefines the
      <code><a href="https://www.w3.org/TR/activitystreams-vocabulary/#dfn-content">content</a></code> and
      <code><a href="https://www.w3.org/TR/activitystreams-vocabulary/#dfn-summary">summary</a></code>
      properties as natural language values which means their values can be expressed
      as either a string or an object mapping language tags to string values.
      In the 1.0 syntax, these are expressed solely as String values.  Because
      the 1.0 values are a valid subse