def set_pandoc_ruby_options(flag, argument = nil)
      case flag
      when 't', 'to'
        @writer = argument.to_s
        @binary_output = true if BINARY_WRITERS.keys.include?(@writer)
      end
    end
def set_pandoc_ruby_options(flag, argument = nil)
      case flag
      when 't', 'to'
        @writer = argument.to_s
        @binary_output = true if BINARY_WRITERS.keys.include?(@writer)
      end
    end
Takes an option and optional argument and uses them to set any flags
 used by RubyPandoc.