   is run if the test case has no tests or all tests have been filtered out.
 
   `setup` and `setup_all` callbacks can be defined by a block, by passing
-  an atom naming a unary function, or by passing a list of such
+  an atom naming a one-arity function, or by passing a list of such
   atoms. Both can opt to receive the current context by specifying it
   as parameter if defined by a block. Functions used to define a test
   setup must accept the context as single argument.

  @doc """
  Defines a callback to be run before all tests in a case.

  Pass a block or name of a unary function as atom, or list of such
  atoms.

  Can return values to be merged into the context, to set up state for
  tests. For more details, see the "Context" section shown above.

  ## Examples

  @doc """
  Defines a callback to be run before each test in a case.

  Accepts a block or the name of a one-arity function in the form of an atom,
  or a list of such atoms.

  Can return values to be merged into the `context`, to set up the state for
  tests. For more details, see the "Context" section shown above.

  ## Examples
