The non-blank variable names on the left side of <code>:=</code>
must be <a href="#Uniqueness_of_identifiers">unique</a>.
</p>

<pre>
field1, offset := nextField(str, 0)
field2, offset := nextField(str, offset)  // redeclares offset
x, y, x := 1, 2, 3                        // illegal: x repeated on left side of :=
</pre>

<p>