class_docstr: References
  ==========
  
  .. [1] Holt, D., Eick, B., O'Brien, E.
         "Handbook of Computational Group Theory"
         Section 8.1.3
class_docstr_tok: ["References","==========","..","[","1","]","Holt",",","D.",",","Eick",",","B.",",","O'Brien",",","E.","``","Handbook","of","Computational","Group","Theory","''","Section","8.1.3"]
code: def _sift(self, z, g):
      h = g
      d = self.depth(h)
      while d < len(self.pcgs) and z[d - 1] != 1:
          k = z[d - 1]
          e = (
              self.leading_exponent(h)
              * (self.leading_exponent(k)) ** -1
          )
          e = e % self.relative_order[d - 1]
          h = k**-e * h
          d = self.depth(h)
      return h
  
imports: from sympy.ntheory.primetest import isprime
  from sympy.combinatorics.perm_groups import PermutationGroup
  from sympy.printing.defaults import DefaultPrinting
  from sympy.combinatorics.free_groups import free_group
label_desc: Use image node_id 11 for calling the Collector obj's underlying member method code with example usage: obj._sift(z, g) and returns: h