Use an explicit function argument for `iterate`

Also replace :hello with "hello" to avoid potential confusion since
:hello is also a function.

refs #75

resources/koans.clj

@@ -127,7 +127,7 @@
                           [0 1 2 3 4]
                           10
                           95
-                          (range 20)
+                          [1 2 4 8 16 32 64 128]
                           :a]
                     "___" [(fn [x] x)]}]
 

src/koans/11_lazy_sequences.clj

@@ -17,12 +17,12 @@
      (drop __ (range 100)))
 
   "Iteration provides an infinite lazy sequence"
-  (= __ (take 20 (iterate inc 0)))
+  (= __ (take 8 (iterate (fn [x] (* x 2)) 1)))
 
   "Repetition is key"
   (= [:a :a :a :a :a :a :a :a :a :a]
      (repeat 10 __))
 
   "Iteration can be used for repetition"
-  (= (repeat 100 :hello)
-     (take 100 (iterate ___ :hello))))
+  (= (repeat 100 "hello")
+     (take 100 (iterate ___ "hello"))))