# File lib/facet/lisp-format.rb, line 344
      def modifiers
        modifiers = []
        while have_more_input
          ch = next_char
          if ch == ?: or ch == ?@
            unless modifiers.include? ch
              modifiers << ch
            else
              raise ModifierError.new(@pos), "duplicate #{ch.chr} modifier"
            end
          else
            unget_char
            break
          end
        end
        return modifiers
      end