code: def test_linear_at_zero(self):
      w = waveforms.chirp(t=0, f0=1.0, f1=2.0, t1=1.0, method="linear")
      assert_almost_equal(w, 1.0)
  
imports: import numpy
  from numpy.testing import assert_almost_equal, assert_equal, assert_, assert_allclose, assert_array_equal
  from pytest import raises
  import scipy.signal.waveforms
label_desc: Use image node_id 1 for calling the TestChirp obj's underlying member method code with example usage: obj.test_linear_at_zero() without return types