calling <code>twoprint</code> will call <code>setup</code> exactly
once.
The <code>setup</code> function will complete before either call
of <code>print</code>.
The result will be that <code>"hello, world"</code> will be printed
twice.
</p>

<h3 id="atomic">Atomic Values</h3>

<p>
The APIs in the <a href="/pkg/sync/atomic/"><code>sync/atomic</code></a>
package are collectively “atomic operations”

<a href="#Function_declarations">function</a>,
<a href="#Labeled_statements">label</a>, or
<a href="#Import_declarations">package</a>.
Every identifier in a program must be declared.
No identifier may be declared twice in the same block, and
no identifier may be declared in both the file and package block.
</p>

<p>
The <a href="#Blank_identifier">blank identifier</a> may be used like any other identifier

<a href="#Function_declarations">function</a>,
<a href="#Labeled_statements">label</a>, or
<a href="#Import_declarations">package</a>.
Every identifier in a program must be declared.
No identifier may be declared twice in the same block, and
no identifier may be declared in both the file and package block.
</p>

<p>
The <a href="#Blank_identifier">blank identifier</a> may be used like any other identifier