# File lib/sass/script/value/string.rb, line 121
    def check_deprecated_interp
      return unless @deprecated_interp_equivalent

      # rubocop:disable GlobalVars
      $_sass_deprecated_interp_warnings ||= Set.new
      key = [source_range.start_pos.line, source_range.file, @deprecated_interp_equivalent]
      return if $_sass_deprecated_interp_warnings.include?(key)
      $_sass_deprecated_interp_warnings << key
      # rubocop:enable GlobalVars

      location = "on line #{source_range.start_pos.line}"
      location << " of #{source_range.file}" if source_range.file
      Sass::Util.sass_warn "DEPRECATION WARNING \#{location}: \\\#{} interpolation near operators will be simplified\nin a future version of Sass. To preserve the current behavior, use quotes:\n\n  \#{@deprecated_interp_equivalent}\n"
    end