observing the write to <code>done</code>
implies observing the write to <code>a</code>, so this program could
print an empty string too.
Worse, there is no guarantee that the write to <code>done</code> will ever
be observed by <code>main</code>, since there are no synchronization
events between the two threads.  The loop in <code>main</code> is not
guaranteed to finish.
</p>

<p>

iteration values from 0 up to <code>len(a)-1</code> and does not index into the array
or slice itself. For a <code>nil</code> slice, the number of iterations is 0.
</li>

<li>
For a string value, the "range" clause iterates over the Unicode code points
in the string starting at byte index 0.  On successive iterations, the index value will be the
index of the first byte of successive UTF-8-encoded code points in the string,

'\k'         // illegal: k is not recognized after a backslash
'\xa'        // illegal: too few hexadecimal digits
'\0'         // illegal: too few octal digits
'\400'       // illegal: octal value over 255
'\uDFFF'     // illegal: surrogate half
'\U00110000' // illegal: invalid Unicode code point
</pre>


<h3 id="String_literals">String literals</h3>

<p>