code: def test_fft_load_aux(self, xp, dtype):
      fft = xp.fft.fft
      c = _load_callback_with_aux2
      if dtype == np.complex64:
          cb_load = _set_load_cb(
              c, "x.x", "cufftComplex", "cufftCallbackLoadC", "float"
          )
      else:
          cb_load = _set_load_cb(
              c,
              "x.x",
              "cufftDoubleComplex",
              "cufftCallbackLoadZ",
              "double",
          )
  
      a = testing.shaped_random(self.shape, xp, dtype)
      out_last = self.n if self.n is not None else self.shape[-1]
      out_shape = list(self.shape)
      out_shape[-1] = out_last
      last_min = min(self.shape[-1], out_last)
      b = xp.arange(
          np.prod(out_shape), dtype=xp.dtype(dtype).char.lower()
      )
      b = b.reshape(out_shape)
      if xp is np:
          x = np.zeros(out_shape, dtype=dtype)
          x[..., 0:last_min] = a[..., 0:last_min]
          x.real *= b
          out = fft(x, n=self.n, norm=self.norm)
          if dtype in (np.float32, np.complex64):
              out = out.astype(np.complex64)
      else:
          with use_temporary_cache_dir():
              with xp.fft.config.set_cufft_callbacks(
                  cb_load=cb_load, cb_load_aux_arr=b
              ):
                  out = fft(a, n=self.n, norm=self.norm)
  
      return out
  
imports: import contextlib
  import string
  import sys
  import tempfile
  from unittest import mock
  import numpy
  import pytest
  import cupy
  from cupy import testing
label_desc: Use image node_id 16 for calling the Test1dCallbacks obj's underlying member method code with example usage: obj.test_fft_load_aux(xp, dtype) and returns: out