code: def deriv3_inverse(self, phi, theta):
      et = np.exp(theta)
      ept = np.exp(phi + theta)
      d3 = -(
          ((et - 1) * ept * (ept + et - 1))
          / (theta * (ept - et + 1) ** 3)
      )
      return d3
  
imports: import warnings
  import numpy
  from scipy.special import expm1, gamma
label_desc: Use image node_id 6 for calling the TransfFrank obj's underlying member method code with example usage: obj.deriv3_inverse(phi, theta) and returns: d3