indirection <code>*x</code> denotes the <a href="#Variables">variable</a> of type <code>T</code> pointed
to by <code>x</code>.
If <code>x</code> is <code>nil</code>, an attempt to evaluate <code>*x</code>
will cause a <a href="#Run_time_panics">run-time panic</a>.
</p>

<pre>
&amp;x
&amp;a[f(2)]
&amp;Point{2, 3}
*p
*pf(x)

var x *int = nil

}
</pre>

<p>
it can happen that <code>g</code> prints <code>2</code> and then <code>0</code>.
</p>

<p>
This fact invalidates a few common idioms.
</p>

<p>
Double-checked locking is an attempt to avoid the overhead of synchronization.
For example, the <code>twoprint</code> program might be
incorrectly written as:
</p>

<pre>
var a string
var done bool

func setup() {

type is a <a href="#Type_parameter_declarations">type parameter</a> with an empty
<a href="#Interface_types">type set</a>. Functions with such type parameters
cannot be <a href="#Instantiations">instantiated</a>; any attempt will lead
to an error at the instantiation site.
</p>

<h3 id="Qualified_identifiers">Qualified identifiers</h3>

<p>
A <i>qualified identifier</i> is an identifier qualified with a package name prefix.