call.rb

args << generate_payload(options) if [:post, :put].include?(method)

 def generate_payload(options)
      if options[:payload].is_a?(String)
        return options[:payload]
      elsif options[:payload].is_a?(Hash)
        return format_payload(options[:payload])
      end
 end

 def format_payload(payload)
      if !payload.nil?
        if payload[:optional]
          if payload[:required]
            payload = payload[:required].merge(payload[:optional])
          else
            payload = payload[:optional]
          end
        elsif options[:payload][:delta]
          payload = payload
        else
          payload = payload[:required]
        end
      else
        payload = {}
      end

    return payload.to_json
  end

The method upload_bits would thus call:

call(:put, path("#{upload_id}/#{offset}/"), :payload => content)