e class="fsharp"><a
      href="../reference/primitives.html#members.Error"><span class="ci">Error</span></a></code> and the error message to <code class="fsharp"><span
      class="ci">error</span></code>. The <code class="fsharp"><a href="../reference/reply.html"><span class="ci">Reply</span></a></code> type also
      defines a 3‐argument constructor, which simply sets the fields to the respective argument values. The default valuetype constructor with 0
      arguments initializes the <code class="fsh