code: def chirp_hyperbolic(t, f0, f1, t1):
      f = f0 * f1 * t1 / ((f0 - f1) * t + f1 * t1)
      return f
  
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 4 for calling a global function with example usage: chirp_hyperbolic(t, f0, f1, t1) and returns: f