ure is
encountered. Running the code on &#8216;<code>a + 2</code>&#8217; for example outputs:</p>
<pre class="output">  
Expected one of [SUM, INTEGER] at line 1 char 1.
|- Failed to match sequence (INTEGER OPERATOR EXPRESSION) at line 1 char 1.
|  `- Failed to match sequence ([0-9]{1, } SPACE?) at line 1 char 1.
|     `- Expected at least 1 of [0-9] at line 1 char 1.
|        `- Failed to match [0-9] at line 1 char 1.
`- Failed to match sequence ([0-9]{1, } SPACE?) at line 1 char 1.
   `- Expected at least