   defmacro case(condition, blocks)
 
   @doc """
-  Execute the given expressions and catch any error, exit
+  Evaluate the given expressions and catch any error, exit
   or throw that may have happened.
 
   ## Examples

  end

  @doc """
  Provides an unless macro that executes the expression
  unless a value evaluates to true. Check `if` for examples
  and documentation.
  """
  defmacro unless(clause, options) do
    do_clause   = Keyword.get(options, :do, nil)

        value -> value
      end

  In the example above, we compare `thing` with each given match clause and
  evaluate the expression corresponding to the first clause that matches. If no
  clause matches, an error is raised.

  Since Elixir variables can be assigned more than once, variables
