You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: extend_node.rb
    path of file: ./repos/stackneveroverflow/vendor/bundle/ruby/2.3.0/gems/sass-3.4.24/lib/sass/tree
    
    the code of the file until where you have to start completion: require 'sass/tree/node'

module Sass::Tree
  # A static node representing an `@extend` directive.
  #
  # @see Sass::Tree
  class ExtendNode < Node
    # The parsed selector after interpol
    
    def optional?; @optional; end

    # @param selector [Array<String, Sass::Script::Tree::Node>]
    #   The CSS selector to extend,
    #   interspersed with {Sass::Script::Tree::Node}s
    #   representing `#{}`-interpolation.
    # @param optional [Boolean] See \{ExtendNode#optional?}
    # @param selector_source_range [Sass::Source::Range] The extended selector source range.
    def initialize(selector, optional, selector_source_range)
      @selector = selector
      @optional = optional
      @selector_source_range = selector_source_range
      super()
    end
  end