code: def __getitem__(self, varidx):
      major, minor = varidx >> 16, varidx & 0xFFFF
      if varidx == NO_VARIATION_INDEX:
          return 0.0
      varData = self._varData
      scalars = [
          self._getScalar(ri) for ri in varData[major].VarRegionIndex
      ]
      deltas = varData[major].Item[minor]
      return self.interpolateFromDeltasAndScalars(deltas, scalars)
  
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 6 for calling the VarStoreInstancer obj's underlying member method code with example usage: obj.__getitem__(varidx) and returns: self, int