Add Not So Random as a go til.

go/not-so-random.md

@@ -0,0 +1,46 @@
+# Not So Random
+
+Go's `rand` package makes it easy to generate all sorts of random numbers.
+What they don't tell you though is that the default seed is `1`. So if you
+write a program like so:
+
+```go
+package main
+
+import "fmt"
+import "math/rand"
+
+func main() {
+    stuff := []string{
+        "one",
+        "two",
+        "three",
+        "four",
+    }
+    fmt.Println(stuff[rand.Intn(len(stuff))])
+}
+```
+
+and then run it, you will get output like:
+
+```
+three
+```
+
+and any subsequent runs of the program will continue to produce `three`. Not
+exactly what we are looking for.
+
+If you want your program to be a little less predictable, you will want to
+seed it yourself, perhaps with the current time, instead of `1`. Try adding
+the following to the beginning of the `main` function:
+
+```go
+rand.Seed( time.Now().UTC().UnixNano())
+```
+
+You'll also want to import the `time` package.
+
+Things should *appear* to be a bit more random now.
+
+source: [Jake Worth](https://twitter.com/jwworth) and
+[Stackoverflow](http://stackoverflow.com/questions/12321133/golang-random-number-generator-how-to-seed-properly)