code: def _create(self):
          
          from samplerate.lowlevel import ffi, src_callback_new, src_delete
          from samplerate.exceptions import ResamplingError
  
          state, handle, error = src_callback_new(
              self._callback, self._converter_type.value, self._channels)
          if error != 0:
              raise ResamplingError(error)
          self._state = ffi.gc(state, src_delete)
          self._handle = handle
docs: Create new callback resampler.