Simplify atoms koans. Fix #185

lib/koans/05_atoms.ex

@@ -3,29 +3,15 @@ defmodule Atoms do
 
   @intro "Atoms"
 
-  koan "Atoms are sort of like strings" do
+  koan "Atoms are constants where their name is their own value" do
     adam = :human
     assert adam == ___
   end
 
-  koan "Strings can be converted to atoms, and vice versa" do
-    assert String.to_atom("atomized") == ___
-    assert Atom.to_string(:stringified) == ___
-  end
-
   koan "It is surprising to find out that booleans are atoms" do
     assert is_atom(true) == ___
-    assert is_atom(false) == ___
+    assert is_boolean(false) == ___
     assert :true == ___
     assert :false == ___
   end
-
-  koan "Modules are also atoms" do
-    assert is_atom(String) == ___
-  end
-
-  koan "Functions can be called on the atom too" do
-    assert :"Elixir.String" == String
-    assert :"Elixir.String".upcase("hello") == ___
-  end
 end

test/koans/atoms_koans_test.exs

@@ -5,10 +5,7 @@ defmodule AtomsTests do
   test "Atoms" do
     answers = [
       :human,
-      {:multiple, [:atomized, "stringified"]},
       {:multiple, [true, true, true, false]},
-      true,
-      "HELLO",
     ]
 
     test_all(Atoms, answers)