Implement inheritance

[zavr-1]

<type name="Message" desc="A TypeScript Server message">
    <prop number name="seq">
      Sequence number of the message
    </prop>
    <prop name="type" type="'request'|'response'|'event'">
      One of "request", "response", or "event"
    </prop>
  </type>
<type name="Event" desc="Server-initiated event message" extends="Message">
    <prop name="type" type="'event'" />
    <prop string name="event">
      Name of event
    </prop>
    <prop opt name="body">
      Event-specific information
    </prop>
  </type>

[zavr-1]

microsoft/TypeScript#20077

/**
 * @typedef {Object} ChildType
 * @property {String} childProp
 *
 * @typedef {Base & ChildType} Child
 */

but only for TS