[isabelle] apply a rewriting-lemma only once



Hello,
how can i apply the following lemma only once?
lemma "a = a + 1"  (the soundness of the lemma is here irrelevant)
I mean i only want to rewrite the "a" with "a+1" only once..cause by default it will rewrite forever and i dont want that.
Thank you! 		 	   		  


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