code: private synchronized boolean cancel(final int id, final boolean mayInterrupt,
              final boolean removeOperation) {
          final RunningOperation runningOperation = mRunningOperations.get(id);
          if (runningOperation != null) {
              if (removeOperation) {
                  mRunningOperations.remove(id);
              }
              mCancelledOperations.add(id);
              return runningOperation.cancel(mayInterrupt);
          } else {
              return false;
          }
      }
docs: Cancels running operation.
  
  @param id              the unique id of operations' launch
  @param mayInterrupt    {@code true} if thread executing operation task should be interrupted;
  otherwise, in-progress tasks are allowed to complete
  @param removeOperation {@code true} if the operation should be marked as removed
  @return {@code false} if the task could not be cancelled, typically because it has already
  completed normally; {@code true} otherwise