Enumerate the exercises

03_hamming_distance.lua

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+-- The hamming distance is the number of positions in which two
+-- strings differ, and is used to measure how similar strings are.
+-- Implement the hamming_distance() function below to calculate this;
+-- you may assume that the strings are of equal length.
+--
+-- Solution --------------------------------------------------------------------
+function hamming_distance(str1, str2)
+	-- Your implementation here
+end
+
+-- Tests -----------------------------------------------------------------------
+
+local luaunit = require("luaunit.luauint")
+
+function test_distance_between_foo_and_bar_is_3()
+	luaunit.assertEquals(hamming_distance("foo", "bar"), 3)
+end
+
+function test_distance_between_bar_and_baz_is_1()
+	luaunit.assertEquals(hamming_distance("bar", "baz"), 1)
+end
+
+os.exit(luaunit.LuaUnit.run())