AttributeError: module 'Kurtosis' has no attribute 'Kurtosis_c'

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I am trying to build a sink block with FFT and Kurtosis capability using gr_modtool.

The code itself can be compiled without error.

But when I run the flow graph in GRC, it produces following error message.

Generating: '/home/nomo/gr-Kurtosis/kurtosis.py'

Executing: /usr/bin/python3 -u /home/nomo/gr-Kurtosis/kurtosis.py

Traceback (most recent call last):
  File "/home/nomo/gr-Kurtosis/kurtosis.py", line 134, in <module>
    main()
  File "/home/nomo/gr-Kurtosis/kurtosis.py", line 112, in main
    tb = top_block_cls()
  File "/home/nomo/gr-Kurtosis/kurtosis.py", line 81, in __init__
    self.Kurtosis_Kurtosis_c_0 = Kurtosis.Kurtosis_c(1024)
AttributeError: module 'Kurtosis' has no attribute 'Kurtosis_c'

Below is the implmentation source file:

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <gnuradio/io_signature.h>
#include "Kurtosis_c_impl.h"

namespace gr {
  namespace Kurtosis {

    Kurtosis_c::sptr
    Kurtosis_c::make(int fftsize)
    {
      return gnuradio::get_initial_sptr
        (new Kurtosis_c_impl(fftsize));
    }


    /*
     * The private constructor
     */
    Kurtosis_c_impl::Kurtosis_c_impl(int fftsize)
      : gr::sync_block("Kurtosis_c",
              gr::io_signature::make(1, 1, sizeof(gr_complex)),
              gr::io_signature::make(0, 0, 0)),
              d_N(fftsize)
    {
      d_input = (fftw_complex*)fftw_malloc(sizeof(gr_complex) * d_N);
      K = (fftw_complex*)fftw_malloc(sizeof(gr_complex) * d_N);
      d_plan = fftw_plan_dft_1d(d_N, d_input, d_input, FFTW_BACKWARD, FFTW_ESTIMATE);
    }

    /*
     * Our virtual destructor.
     */
    Kurtosis_c_impl::~Kurtosis_c_impl()
    {
    }

    int
    Kurtosis_c_impl::work(int noutput_items,
        gr_vector_const_void_star &input_items,
        gr_vector_void_star &output_items)
    {
      const gr_complex *in = (const gr_complex*) input_items[0];

      for(int i = 0; i < noutput_items; i++)
      {
        d_input[i][0] = in[i].real();
        d_input[i][1] = in[i].imag();
      }
      
      fftw_execute(d_plan);
      
      for(int i = 0; i < noutput_items ;i++)
      {   
        S1[i][0] = S1[i][0] + d_input[i][0];
        S1[i][1] = S1[i][1] + d_input[i][1];
	    
        S2[i][0] = S2[i][0] + d_input[i][0] * d_input[i][0];
        S2[i][1] = S2[i][1] + d_input[i][1] * d_input[i][1];
	    
        S3[i][0] = S3[i][0] + d_input[i][0] * d_input[i][0] * d_input[i][0];
        S3[i][1] = S3[i][1] + d_input[i][1] * d_input[i][1] * d_input[i][1];
	    
        S4[i][0] = S4[i][0] + d_input[i][0] * d_input[i][0] * d_input[i][0] * d_input[i][0];
        S4[i][1] = S4[i][1] + d_input[i][1] * d_input[i][1] * d_input[i][1] * d_input[i][1];
	    
        dc[i][0] = dc[i][0] + 1;
        dc[i][1] = dc[i][1] + 1;
      }
	
      for(int i = 0; i < noutput_items; i++)
      {
        Myu1[i][0] = S1[i][0] / dc[i][0];
        Myu1[i][1] = S1[i][1] / dc[i][1];
	  
        Myu2[i][0] = S2[i][0] / dc[i][0];
        Myu2[i][1] = S2[i][1] / dc[i][1];
	  
        Myu3[i][0] = S3[i][0] / dc[i][0];
        Myu3[i][1] = S3[i][1] / dc[i][1];
	  
        Myu4[i][0] = S4[i][0] / dc[i][0];
        Myu4[i][1] = S4[i][1] / dc[i][1];
      }

	

      for(int i = 0; i < noutput_items; i++)
      {
        K[i][0] = (Myu4[i][0] - 4 * Myu3[i][0] * Myu1[i][0] + 6 * Myu2[i][0] * Myu1[i][0] 
                   * Myu1[i][0] - 3 * Myu1[i][0] * Myu1[i][0] * Myu1[i][0] * Myu1[i][0]) / 
                    ((Myu2[i][0] - Myu1[i][0] * Myu1[i][0]) * (Myu2[i][0] - Myu1[i][0] 
                      * Myu1[i][0]));
	  
        K[i][1] = (Myu4[i][1] - 4 * Myu3[i][1] * Myu1[i][1] + 6 * Myu2[i][1] * Myu1[i][1] 
                   * Myu1[i][1] - 3 * Myu1[i][1] * Myu1[i][1] * Myu1[i][1] * Myu1[i][1]) / 
                    ((Myu2[i][1] - Myu1[i][1] * Myu1[i][1]) * (Myu2[i][1] - Myu1[i][1] 
                      * Myu1[i][1]));
      }

      // Tell runtime system how many output items we produced.
      return noutput_items;
    }

  } /* namespace Kurtosis1 */
} /* namespace gr */

The implementation header file is as below:

#ifndef INCLUDED_KURTOSIS1_KURTOSIS_C1_IMPL_H
#define INCLUDED_KURTOSIS1_KURTOSIS_C1_IMPL_H

#include <Kurtosis/Kurtosis_c.h>
#include <fftw3.h>

namespace gr {
  namespace Kurtosis {

    class Kurtosis_c_impl : public Kurtosis_c
    {
     private:
       int d_N;
       
        
       fftw_complex *K;
       fftw_complex *S1;
       fftw_complex *S2;
       fftw_complex *S3; 
       fftw_complex *S4;
       fftw_complex *Myu1;
       fftw_complex *Myu2;
       fftw_complex *Myu3;
       fftw_complex *Myu4;
       fftw_complex *dc;
       
   
      
       fftw_complex *d_input;
       fftw_plan     d_plan;

     public:
      Kurtosis_c_impl(int fftsize);
      ~Kurtosis_c_impl();
     

      // Where all the action really happens
      int work(
              int noutput_items,
              gr_vector_const_void_star &input_items,
              gr_vector_void_star &output_items
      );
    };

  } // namespace Kurtosis1
} // namespace gr

#endif /* INCLUDED_KURTOSIS1_KURTOSIS_C1_IMPL_H */

Question: How to solve this error?

Thank you in advance for any guidance you may be able to provide.