<p>To run multiple chains given a model and data, either sequentially or in parallel,
we can also use the Unix or DOS shell <code>for</code> loop to set up index variables needed to identify
each chain and its outputs.</p>
<p>On MacOS or Linux, the for-loop syntax for both the bash and zsh interpreters
is:</p>
<pre><code>for NAME [in LIST]; do COMMANDS; done</code></pre>
<p>The list can be a simple sequence of numbers, or you can use the shell expansion syntax <code>{1..N}</code>
which expands to the sequen