Initial draft for strings

lib/koans/03_strings.ex

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+defmodule Strings do
+  use Koans
+
+  koan "Strings are there to represent text" do
+    assert "hello" == "hello"
+  end
+
+  koan "They can be put together" do
+    assert "hello world" == "hello " <> "world"
+  end
+
+  koan "Or pulled apart when needed" do
+    assert ["hello", "world"] == String.split("hello world")
+  end
+
+  koan "Be careful, a message may be altered" do
+    assert "An awful day" == String.replace("An incredible day", "incredible", "awful")
+  end
+
+  koan "But strings never lie about themselves" do
+    assert true == String.contains?("An incredible day", "incredible")
+  end
+
+  koan "Sometimes you want just the opposite of what is given" do
+    assert "banana" == String.reverse("ananab")
+  end
+
+  koan "Other times a little cleaning is in order" do
+    assert "banana" == String.strip("  \n banana\n  ")
+  end
+
+  koan "Repetition is the mother of learning" do
+    assert "StringStringString" == String.duplicate("String", 3)
+  end
+
+  koan "Strings can be louder when necessary" do
+    assert "LISTEN" == String.upcase("listen")
+  end
+end