Better handling of QuantumKernel -> KernelSignature

    os << derived.parent_kernel->toString() << "\n";

  }

  static void print_kernel(Args... args) {

    Derived derived(args...);

    derived.disable_destructor = true;

    derived(args...);

    xacc::internal_compiler::execute_pass_manager();

    std::cout << derived.parent_kernel->toString() << "\n";

  }

  static void print_kernel(Args... args) { print_kernel(std::cout, args...); }

  // Static method to query how many instructions are in this kernel

  static std::size_t n_instructions(Args... args) {

  KernelSignature(callable_function_ptr<Args...> &&f) : function_pointer(f) {}

  template <typename KernelType>

  // CTor from a QCOR QuantumKernel instance:

  template <

      typename KernelType,

      std::enable_if_t<

          std::is_base_of_v<QuantumKernel<KernelType, Args...>, KernelType>,

          bool> = true>

  KernelSignature(KernelType &kernel)

      : function_pointer(*readOnly),

        lambda_func(

            [&](std::shared_ptr<xacc::CompositeInstruction> pp, Args... a) {

              // Expand the kernel and append to the *externally-provided*

              // parent kernel as a KernelSignature one.

              kernel.disable_destructor = true;

              kernel.parent_kernel = pp;

              kernel(a...);

              pp->addInstructions(kernel.parent_kernel->getInstructions());

            }) {}

  // Ctor from raw void* function pointer.