code: def deriv2(self, t, theta):
      t = np.asarray(t)
      tmp = np.exp(theta * t)
      d2 = -(theta**2) * tmp / (tmp - 1) ** 2
      return d2
  
imports: import warnings
  import numpy
  from scipy.special import expm1, gamma
label_desc: Use image node_id 4 for calling the TransfFrank obj's underlying member method code with example usage: obj.deriv2(t, theta) and returns: d2