OP_PICK 3 x0 x1 x2 x3 For the above stack ,OP_PICK should return x3, but it returns x2 see: [build/script_interpreter/interpreter.js#L278](https://github.com/siminchen/bitcoinIDE/blob/bd45f410ce5458a3e88800e1f76fb8fd45f388c8/build/script_interpreter/interpreter.js#L278)