regression-calc.dfy(8,16): Error: a postcondition could not be proved on this return path
regression-calc.dfy(8,10): Related location: this is the postcondition that could not be proved
regression-calc.dfy(15,16): Error: a postcondition could not be proved on this return path
regression-calc.dfy(15,10): Related location: this is the postcondition that could not be proved

Dafny program verifier finished with 0 verified, 2 errors
