code: def _hash(s, hashbits):
      # A variable-length version of Python's builtin hash
      if s == "":
          return 0
      else:
          x = ord(s[0]) << 7
          m = 1000003
          mask = 2**hashbits - 1
          for c in s:
              x = ((x * m) ^ ord(c)) & mask
          x ^= len(s)
          if x == -1:
              x = -2
          return x
  
imports: from __future__ import division
  import random
  from collections import defaultdict
  from math import log
  from whoosh.compat import xrange, iteritems
label_desc: Use image node_id 3 for calling a global function with example usage: _hash(s, hashbits) and returns: int, x