   end
 
   @doc """
-  Returns true if `term` is a pid (process identifier); otherwise returns false.
+  Returns `true` if `term` is a pid (process identifier); otherwise returns `false`.
 
   Allowed in guard tests.
   """

  end

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

  Allowed in guard tests.
  """

  end

  @doc """
  Returns `true` if `term` is a reference; otherwise returns `false`.

  Allowed in guard tests.
  """
