yield-ensures.dfy(8,24): Error: possible violation of yield-ensures condition
 Asserted expression: count == val
yield-ensures.dfy(5,25): Related location: this proposition could not be proved
yield-ensures.dfy(8,24): Error: possible violation of yield-ensures condition
 Asserted expression: 0 <= -i && -i <= count
yield-ensures.dfy(6,18): Related location: this proposition could not be proved
yield-ensures.dfy(18,4): Error: possible violation of yield-ensures condition
 Asserted expression: this.out == val
yield-ensures.dfy(12,25): Related location: this proposition could not be proved
yield-ensures.dfy(18,4): Error: possible violation of yield-ensures condition
 Asserted expression: 0 <= this.index && this.index <= count
yield-ensures.dfy(13,18): Related location: this proposition could not be proved

Dafny program verifier finished with 2 verified, 4 errors
