code: public void stitch(String spaceId, String manifestId, File toDir)
          throws Exception {
          verifyDir(toDir);
  
          Content content = stitcher.getContentFromManifest(spaceId, manifestId);
          writeContentToDir(content, toDir);
      }
docs: This method retrieves the chunks manifest specified by the arg space-id
  and manifest-id (content-id), then reconstitues the chunks defined in
  the manifest into the original file at the arg to-directory.
  
  @param spaceId    containing chunks manifest
  @param manifestId of the manifest (content-id)
  @param toDir      destination of reconstituted original content item
  @throws Exception on error