code: func opcodeSha1(op *parsedOpcode, vm *Engine) error {
  	buf, err := vm.dstack.PopByteArray()
  	if err != nil {
  		return err
  	}
  
  	hash := sha1.Sum(buf)
  	vm.dstack.PushByteArray(hash[:])
  	return nil
  }
docs: // opcodeSha1 treats the top item of the data stack as raw bytes and replaces it
  // with sha1(data).
  //
  // Stack transformation: [... x1] -> [... sha1(x1)]