code: def memcpy_dtoh(self, dest, src):
          
          if isinstance(src, cl.Buffer):
              cl.enqueue_copy(self.queue, dest, src)
docs: perform a device to host memory copy
  
          :param dest: A numpy array in host memory to store the data
          :type dest: numpy.ndarray
  
          :param src: An OpenCL Buffer to copy data from
          :type src: pyopencl.Buffer