code: def mapFeatures(self, featureMap):
      self.FeatureIndex = [featureMap[i] for i in self.FeatureIndex]
      if self.ReqFeatureIndex != 65535:
          self.ReqFeatureIndex = featureMap[self.ReqFeatureIndex]
  
imports: from fontTools import ttLib
  from fontTools.ttLib.tables.DefaultTable import DefaultTable
  from fontTools.ttLib.tables import otTables
  from fontTools.merge.base import add_method, mergeObjects
  from fontTools.merge.util import *
  import logging
label_desc: Use image node_id 18 for calling a global function with example usage: mapFeatures(featureMap) without return types