code: def _columns(chars):
      cols = 0
      i = 1
      while chars:
          if chars & 0b1111:
              cols |= i
          chars >>= 4
          i <<= 1
      return cols
  
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 9 for calling the _Encoding obj's underlying member method code with example usage: obj._columns(chars) and returns: cols