docs: private boolean removeFile(File f) {
          if (Utils.fileIsFile(f)) {
              return Utils.deleteFile(f);
          } else {
              //delete directory f..
              boolean ok = true;
              //remove all the children..
              File children[] = Utils.listFiles(f);
              if (children != null) {
                  for (File child : children) {
                      ok &= removeFile(child);
                  }
              }
              //once children are deleted, remove the directory
              if (ok) {
                  ok &= Utils.deleteFile(f);
              }
              return ok;
          }
      }