# File lib/sass/script/string_interpolation.rb, line 24
    def to_sass(opts = {})
      # We can get rid of all of this when we remove the deprecated :equals context
      before_unquote, before_quote_char, before_str = parse_str(@before.to_sass(opts))
      after_unquote, after_quote_char, after_str = parse_str(@after.to_sass(opts))
      unquote = before_unquote || after_unquote ||
        (before_quote_char && !after_quote_char && !after_str.empty?) ||
        (!before_quote_char && after_quote_char && !before_str.empty?)
      quote_char =
        if before_quote_char && after_quote_char && before_quote_char != after_quote_char
          before_str.gsub!("\\'", "'")
          before_str.gsub!('"', "\\\"")
          after_str.gsub!("\\'", "'")
          after_str.gsub!('"', "\\\"")
          '"'
        else
          before_quote_char || after_quote_char
        end

      res = ""
      res << 'unquote(' if unquote
      res << quote_char if quote_char
      res << before_str
      res << '#{' << @mid.to_sass(opts) << '}'
      res << after_str
      res << quote_char if quote_char
      res << ')' if unquote
      res
    end