generate_class_tree_level

# File railties/lib/rails/api/generator.rb, line 9
  def generate_class_tree_level(classes, visited = {})
    # Only process core extensions on the first visit and remove
    # Active Storage duplicated classes that are at the top level
    # since they aren't nested under a definition of the `ActiveStorage` module.
    if visited.empty?
      classes = classes.reject { |klass| active_storage?(klass) }
      core_exts = classes.extract! { |klass| core_extension?(klass) }

      super.unshift([ "Core extensions", "", "", build_core_ext_subtree(core_exts, visited) ])
    else
      super
    end
  end