available commands:
x: exit
c: define the calculation function with the parameters prev, cur, and i
   prev and cur start with 0; i is the loop variable from 0 to n
     example: 'return cur + i;' computes the sum of 1 to n
     example: 'if (i == 0) { return 1; } else { return cur * i; }' computes the factorial of i
     example: 'if (i <= 2) { return 1; } else { return prev + cur; }' computes the nth Fibonacci number
i: define the number of iterations, i.e, the number n in the examples above
r: Run the calculation loop often, and print the first and last result
t: Run the calculation loop a couple of time, and print timing information for each run
h: Print this help message

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** first: 3240
** last:  3240
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** first: 23416728348467685
** last:  23416728348467685
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** first: 354224848179261915075
** last:  354224848179261915075
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** first: 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
** last:  93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
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