code: def __init__(self, axisTags):
      self._axisTags = axisTags
      self._regionMap = {}
      self._regionList = buildVarRegionList([], axisTags)
      self._store = buildVarStore(self._regionList, [])
      self._data = None
      self._model = None
      self._supports = None
      self._varDataIndices = {}
      self._varDataCaches = {}
      self._cache = {}
  
imports: from fontTools.misc.roundTools import noRound, otRound
  from fontTools.misc.intTools import bit_count
  from fontTools.ttLib.tables import otTables
  from fontTools.varLib.models import supportScalar
  from fontTools.varLib.builder import buildVarRegionList, buildVarStore, buildVarRegion, buildVarData
  from functools import partial
  from collections import defaultdict
  from heapq import heappush, heappop
label_desc: Use image node_id 1 to create a new OnlineVarStoreBuilder object from inherited base classes: object with example: obj = OnlineVarStoreBuilder(axisTags)