code: def negative_effect(positive_effect):
      return np.exp(-np.log(positive_effect))
  
imports: from operator import itemgetter
  import numpy
  import scipy.sparse
  from scipy.sparse import csr_matrix
  from tick.base.simulation import Simu
  from tick.hawkes import SimuHawkesExpKernels, SimuHawkesMulti
  from tick.preprocessing import LongitudinalFeaturesLagger
  from itertools import permutations
  from copy import deepcopy
  from scipy.stats import beta, norm
label_desc: Use image node_id 7 for calling the CustomEffects obj's underlying member method code with example usage: obj.negative_effect(positive_effect) and returns: np