Added fibonacci example

functional_programming/ch01/fibonacci.go

@@ -0,0 +1,18 @@
+package main
+
+import "fmt"
+
+func Fibonacci(x int) int {
+	if x == 0 {
+		return 0
+	} else if x <= 2 {
+		return 1
+	} else {
+		return Fibonacci(x-2) + Fibonacci(x-1)
+	}
+}
+
+func main() {
+	fib := Fibonacci
+	fmt.Printf("%vn", fib(50))
+}