code: public <R1> TransactionFlow<T,R1> map(Function<R,R1> fn){
  		return of(transactionTemplate,transaction.andThen(fn));
  	}
docs: Map from input -&gt; output within the context of a transaction.
  An exception in the mapping process will cause Rollback
  Transaction will be completed once the entire flow has completed
  <pre>
  {@code
  Integer result = TransactionFlow.<Integer>of(transactionTemplate)
  .map(this::load)
  .map(this::save)
  .execute(10)
  .get();
  }
  </pre>
  
  @param fn Map from input type to output type within a transaction
  @return TransactionFlow