Update the random examples

@@ -4,6 +4,7 @@
 
 package main
 
+import "time"
 import "fmt"
 import "math/rand"
 
@@ -25,9 +26,12 @@ func main() {
     fmt.Print((rand.Float64() * 5) + 5)
     fmt.Println()
 
-    // To make the pseudorandom generator deterministic,
-    // give it a well-known seed.
-    s1 := rand.NewSource(42)
+    // The default number generator is deterministic, so it'll
+    // produce the same sequence of numbers each time by default.
+    // To produce varying sequences, give it a seed that changes.
+    // Note that this is not safe to use for random numbers you
+    // intend to be secret, use `crypto/rand` for those.
+    s1 := rand.NewSource(time.Now().UnixNano())
     r1 := rand.New(s1)
 
     // Call the resulting `rand.Rand` just like the

@@ -1,2 +1,2 @@
-f7ce9724ab51b3e90b8d04cf88eaaa8cf2dfd50e
-X973CNW5aa
+6ce1f98d3c22ee8bf02c41b393361d6cd5fff23a
+TZElZIwNU1

@@ -1,4 +1,4 @@
-$ go run random-numbers.go 
+$ go run random-numbers.go
 81,87
 0.6645600532184904
 7.123187485356329,8.434115364335547

@@ -41,7 +41,7 @@ generation.</p>
             
           </td>
           <td class="code leading">
-	        <a href="http://play.golang.org/p/X973CNW5aa"><img title="Run code" src="play.png" class="run" /></a>
+	        <a href="http://play.golang.org/p/TZElZIwNU1"><img title="Run code" src="play.png" class="run" /></a>
             <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -54,7 +54,8 @@ generation.</p>
           </td>
           <td class="code leading">
 	        
-            <div class="highlight"><pre><span class="kn">import</span> <span class="s">&quot;fmt&quot;</span>
+            <div class="highlight"><pre><span class="kn">import</span> <span class="s">&quot;time&quot;</span>
+<span class="kn">import</span> <span class="s">&quot;fmt&quot;</span>
 <span class="kn">import</span> <span class="s">&quot;math/rand&quot;</span>
 </pre></div>
 
@@ -121,13 +122,16 @@ other ranges, for example <code>5.0 &lt;= f' &lt; 10.0</code>.</p>
         
         <tr>
           <td class="docs">
-            <p>To make the pseudorandom generator deterministic,
-give it a well-known seed.</p>
+            <p>The default number generator is deterministic, so it&rsquo;ll
+produce the same sequence of numbers each time by default.
+To make it non-deterministic, give it a seed that changes.
+Note that this is not safe to use for random numbers you
+intend to be secret, use <code>crypto/rand</code> for those.</p>
 
           </td>
           <td class="code leading">
 	        
-            <div class="highlight"><pre>    <span class="nx">s1</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">NewSource</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
+            <div class="highlight"><pre>    <span class="nx">s1</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">NewSource</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">().</span><span class="nx">UnixNano</span><span class="p">())</span>
     <span class="nx">r1</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">New</span><span class="p">(</span><span class="nx">s1</span><span class="p">)</span>
 </pre></div>
 
@@ -179,7 +183,7 @@ produces the same sequence of random numbers.</p>
           </td>
           <td class="code leading">
 	        
-            <div class="highlight"><pre><span class="gp">$</span> go run random-numbers.go 
+            <div class="highlight"><pre><span class="gp">$</span> go run random-numbers.go
 <span class="go">81,87</span>
 <span class="go">0.6645600532184904</span>
 <span class="go">7.123187485356329,8.434115364335547</span>