code: func (vm *Engine) isBranchExecuting() bool {
  	if len(vm.condStack) == 0 {
  		return true
  	}
  	return vm.condStack[len(vm.condStack)-1] == OpCondTrue
  }
docs: // isBranchExecuting returns whether or not the current conditional branch is
  // actively executing.  For example, when the data stack has an OP_FALSE on it
  // and an OP_IF is encountered, the branch is inactive until an OP_ELSE or
  // OP_ENDIF is encountered.  It properly handles nested conditionals.