Sentence:  Felix Kopstein states that `` when the snake reaches its maturity it has already reached about its maximal length '' , but goes on to cite the reticulate python as an <WSD>exception</WSD> , with maximum length approximately three times that at maturity . 
Meaning of the word marked with <WSD> tags:  an instance that does not conform to a rule or generalization; the only exception was her last child"