class_docstr: requires theta >=1
class_docstr_tok: ["requires","theta",">","=1"]
code: def deriv4_inverse(self, phi, theta):
      p = phi  # shorthand
      b = theta
      d4 = (
          (6 * b**3 - 11 * b**2 + 6.0 * b - 1) * p ** (1 / b)
          + (11 * b**2 - 18 * b + 7) * p ** (2 / b)
          + (6 * (b - 1)) * p ** (3 / b)
          + p ** (4 / b)
      ) / (p * b) ** 4
  
      d4 *= np.exp(-(p ** (1 / b)))
      return d4
  
imports: import warnings
  import numpy
  from scipy.special import expm1, gamma
label_desc: Use image node_id 8 for calling the TransfGumbel obj's underlying member method code with example usage: obj.deriv4_inverse(phi, theta) and returns: d4