 develop a small language that allows for simple computation together. 
Here&#8217;s a valid input file for that language:</p>
<pre class="sh_ruby"><code> 
  puts(1 + 2)
  puts(4 + 2)
</code></pre>
<p>To install the parslet library, please do a</p>
<pre><code> 
  gem install parslet
</code></pre>
<p>Now let&#8217;s write the first part of our parser. For now, we&#8217;ll just recognize
simple numbers like &#8216;1&#8217; or &#8216;42&#8217;.</p>
<pre class="sh_ruby"><code title="mini_parser"> 
  require 'pa