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|context> => |context: sw console>


fib |0> => |0>


fib |1> => |1>


n-1 |*> #=> arithmetic(|_self>,|->,|1>)
n-2 |*> #=> arithmetic(|_self>,|->,|2>)
fib |*> #=> arithmetic( fib n-1 |_self>, |+>, fib n-2 |_self>)
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