NetBidirectionalOperator
NetBidirectionalOperator[net] represents a net that applies net to a sequence and to its reverse, concatenating both results into one output sequence.
NetBidirectionalOperator[{fnet,bnet}] uses fnet on the normal input and bnet on the reversed input.
NetBidirectionalOperator[nets,agg] aggregates the two output sequences using the specified aggregation function.
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