code: public static <T,R> TransactionFlow<T,R> of(TransactionTemplate transactionManager,Function<T,R> fn){
  		return new TransactionFlow<>(transactionManager,fn);
  	}
docs: Create a new Transactional Flow
  
  @param transactionManager Spring TransactionTemplate to manage the transactions
  @param fn Initial function to be applied
  @return Create a new Transactional Flow