code: def test_detrend_none(self):
      assert mlab.detrend_none(0.0) == 0.0
      assert mlab.detrend_none(0.0, axis=1) == 0.0
      assert mlab.detrend(0.0, key="none") == 0.0
      assert mlab.detrend(0.0, key=mlab.detrend_none) == 0.0
      for sig in [
          5.5,
          self.sig_off,
          self.sig_slope,
          self.sig_base,
          (self.sig_base + self.sig_slope + self.sig_off).tolist(),
          np.vstack(
              [
                  self.sig_base,  # 2D case.
                  self.sig_base + self.sig_off,
                  self.sig_base + self.sig_slope,
                  self.sig_base + self.sig_off + self.sig_slope,
              ]
          ),
          np.vstack(
              [
                  self.sig_base,  # 2D transposed case.
                  self.sig_base + self.sig_off,
                  self.sig_base + self.sig_slope,
                  self.sig_base + self.sig_off + self.sig_slope,
              ]
          ).T,
      ]:
          if isinstance(sig, np.ndarray):
              assert_array_equal(mlab.detrend_none(sig), sig)
          else:
              assert mlab.detrend_none(sig) == sig
  
imports: from numpy.testing import assert_allclose, assert_almost_equal, assert_array_equal, assert_array_almost_equal_nulp
  import numpy
  import pytest
  from matplotlib import mlab
label_desc: Use image node_id 3 for calling the TestDetrend obj's underlying member method code with example usage: obj.test_detrend_none() without return types