# File lib/facet/lisp-format.rb, line 1592
        def initialize(params, modifiers, top, pos)
          super params, modifiers, top, pos
          unless top.is_a? BeginConditional
            raise SyntaxError.new(@pos),
              '~; directive must be contained within a conditional (~[...~])' +
              ' or a justification (~<...~>)'
          end
        end