def prepare_options(opts = [])
      opts.inject('') do |string, (option, value)|
        string += case
                  when value
                    create_option(option, value)
                  when option.respond_to?(:each_pair)
                    prepare_options(option)
                  else
                    create_option(option)
                  end
      end
    end
def prepare_options(opts = [])
      opts.inject('') do |string, (option, value)|
        string += case
                  when value
                    create_option(option, value)
                  when option.respond_to?(:each_pair)
                    prepare_options(option)
                  else
                    create_option(option)
                  end
      end
    end
Builds the option string to be passed to pandoc by iterating over the
 opts passed in. Recursively calls itself in order to handle hash options.