thing.rb

    def put(thing io, overwrite = false)
      # NOTE: This is an extra call to S3.
      if exists?(thing) && !overwrite
        raise "Thing already exists in S3. Refusing to overwrite"
      end

      metadata = ObjectMetadata.new
      metadata.content_length = io.size
      @client.putObject(bucket, build_key(thing), io.to_inputstream, metadata)
    end