code: func (pop *parsedOpcode) alwaysIllegal() bool {
  	switch pop.opcode.value {
  	case OP_VERIF:
  		return true
  	case OP_VERNOTIF:
  		return true
  	default:
  		return false
  	}
  }
docs: // alwaysIllegal returns whether or not the opcode is always illegal when passed
  // over by the program counter even if in a non-executed branch (it isn't a
  // coincidence that they are conditionals).