   Match can also be used to filter or find a value in an enumerable:
 
       list = [{:a, 1}, {:b, 2}, {:a, 3}]
-      Enum.filter list, match?({:a, _}, _)
+      Enum.filter list, match?({:a, _}, &1)
 
   Guard clauses can also be given to the match:
 

  end

  @doc """
  Returns true if `term` is an atom; otherwise returns false.

  Allowed in guard tests.
  """

  end

  @doc """
  Returns `true` if left is less than or equal to right.
  Like Erlang, Elixir can compare any term. Allowed in guard clauses.

  ## Examples
