{TAIL ~ The flow modification system} 21, wherein the original prefabricated brace and the additional prefabricated brace are secured together with at least one other prefabricated brace similar to the original prefabricated brace in a configuration enclosing {HEAD ~ at least three sides} of a region of the channel 
{ TAIL ~ The flow modification system } 21 , wherein the original prefabricated brace and the additional prefabricated brace are secured together with at least one other prefabricated brace similar to the original prefabricated brace in a configuration enclosing { HEAD ~ at least three sides } of a region of the channel
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