code: synchronized final void cancelAll(final boolean mayInterrupt) {
          for (final Integer key : mRunningOperations.keySet()) {
              cancel(key, mayInterrupt, false);
          }
  
          mRunningOperations.clear();
      }
docs: Cancels all running operations.
  
  @param mayInterrupt {@code true} if threads executing operations task should be interrupted;
  otherwise, in-progress tasks are allowed to complete