code: def powerlaw_pdf(x, a):
      if x > 0:
          return x ** (a - 1)
      return 0.0
  
imports: import math
  import numbers
  import numpy
  from scipy import stats
  from scipy import special
  from ._qmc import check_random_state, Halton, QMCEngine
  from ._unuran.unuran_wrapper import NumericalInversePolynomial
  from scipy._lib._util import check_random_state
label_desc: Use image node_id 23 for calling a global function with example usage: powerlaw_pdf(x, a) and returns: int, unknown