class_docstr: A format that stores positions, character start and end, and
  per-position boost information in each posting.
  
  Supports: frequency, weight, positions, position_boosts, characters,
  character_boosts.
class_docstr_tok: ["A","format","that","stores","positions",",","character","start","and","end",",","and","per-position","boost","information","in","each","posting",".","Supports",":","frequency",",","weight",",","positions",",","position_boosts",",","characters",",","character_boosts","."]
code: def decode_position_boosts(self, valuestring):
      return [
          (pos, boost)
          for pos, _, _, boost in self.decode_character_boosts(
              valuestring
          )
      ]
  
imports: from collections import defaultdict
  from whoosh.analysis import unstopped, entoken
  from whoosh.compat import iteritems, dumps, loads, b
  from whoosh.system import emptybytes
  from whoosh.system import _INT_SIZE, _FLOAT_SIZE
  from whoosh.system import pack_uint, unpack_uint, pack_float, unpack_float
label_desc: Use image node_id 6 for calling the CharacterBoosts obj's underlying member method code with example usage: obj.decode_position_boosts(valuestring) and returns: unknown