# File lib/liquid/block.rb, line 51
    def unknown_tag(tag, params, tokens)
      case tag 
      when 'else'
        raise SyntaxError, "#{block_name} tag does not expect else tag"
      when 'end'
        raise SyntaxError, "'end' is not a valid delimiter for #{block_name} tags. use #{block_delimiter}"
      else
        raise SyntaxError, "Unknown tag '#{tag}'"
      end
    end