generate_class_tree_level

# File railties/lib/rails/api/generator.rb, line 6
  def generate_class_tree_level(classes, visited = {})
    # Only process core extensions on the first visit.
    if visited.empty?
      core_exts, classes = classes.partition { |klass| core_extension?(klass) }

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