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 combine(self, vs):
      s = {}
      for v in vs:
          for pos, sc, ec, boost in self.decode_character_boosts(v):
              if pos in s:
                  old_sc, old_ec, old_boost = pos[s]
                  s[pos] = (
                      min(sc, old_sc),
                      max(ec, old_ec),
                      old_boost + boost,
                  )
              else:
                  s[pos] = (sc, ec, boost)
      poses = [
          (pos, sc, ec, boost)
          for pos, (sc, ec, boost) in sorted(s.items())
      ]
      return self.encode(poses)[0]
  
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 7 for calling the CharacterBoosts obj's underlying member method code with example usage: obj.combine(vs) and returns: self