In [2]: %prun fib(40)
         331160284 function calls (4 primitive calls) in 95.272 seconds

   Ordered by: internal time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
331160281/1   95.272    0.000   95.272   95.272 fib.py:5(fib)
        1    0.000    0.000   95.272   95.272 {built-in method builtins.exec}
        1    0.000    0.000   95.272   95.272 <string>:1(<module>)
        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}

In [3]: %prun fib_tail(40)
         43 function calls (4 primitive calls) in 0.000 seconds

   Ordered by: internal time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
     40/1    0.000    0.000    0.000    0.000 fib.py:12(fib_tail)
        1    0.000    0.000    0.000    0.000 {built-in method builtins.exec}
        1    0.000    0.000    0.000    0.000 <string>:1(<module>)
        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}