src/Loader.php
public function action($hook, $callback, $priority = 10, $accepted_args = 1)
    {
        $this->actions = $this->add($this->actions, $hook, $callback, $priority, $accepted_args);
    }
public function action($hook, $callback, $priority = 10, $accepted_args = 1)
    {
        $this->actions = $this->add($this->actions, $hook, $callback, $priority, $accepted_args);
    }
Add a new action to the collection to be registered with WordPress.

@since   1.0.0
@param   string $hook The name of the WordPress action that is being registered.
@param   callable $callback The name of the function definition on the $component.
@param   int $priority The priority at which the function should be fired.
@param   int $accepted_args The number of arguments that should be passed to the $callback.