# File lib/sass/script/tree/string_interpolation.rb, line 74
    def deep_copy
      node = dup
      node.instance_variable_set('@before', @before.deep_copy) if @before
      node.instance_variable_set('@mid', @mid.deep_copy)
      node.instance_variable_set('@after', @after.deep_copy) if @after
      node
    end