evaluates to true, the "if" branch is executed, otherwise, if
present, the "else" branch is executed.
</p>

<pre class="ebnf">
IfStmt = "if" [ SimpleStmt ";" ] Expression Block [ "else" ( IfStmt | Block ) ] .
</pre>

<pre>
if x &gt; max {
	x = max
}
</pre>

<p>
The expression may be preceded by a simple statement, which
executes before the expression is evaluated.
</p>