text: #ifndef CULAYER_HPP
  #define CULAYER_HPP
  
  #include "particle.hpp"
  #include <cuda.h>
  
  __global__ void particle_step_kernel(int n,
                                       Particle *particles,
                                       int steps,
                                       float const *const sigs_in,
                                       float const *const absorption_rates_in,
                                       float *const weights_absorbed_out,
                                       int min_index,
                                       int max_index,
                                       float dx);
  #endif
  