module AbstractController::Callbacks::ClassMethods

* `except` - The callback should be run for all actions except this action.
* `only` - The callback should be run only for this action.
#### Options

except: :index, if: -> { true } # the :except option will be ignored.

Note that `:if` has priority over `:except` in case they are used together.

only: :index, if: -> { true } # the :if option will be ignored.

Note that `:only` has priority over `:if` in case they are used together.

c.action_name == "index" }`.
The basic idea is that `:only => :index` gets converted to `:if => proc {|c|

`:unless` options of ActiveSupport::Callbacks.
If `:only` or `:except` are used, convert the options into the `:if` and

def _normalize_callback_options(options)
  _normalize_callback_option(options, :only, :if)
  _normalize_callback_option(options, :except, :unless)
end