code: def __merge_classify_context(self):
      class ContextHelper(object):
          def __init__(self, klass, Format):
              if klass.__name__.endswith("Subst"):
                  Typ = "Sub"
                  Type = "Subst"
              else:
                  Typ = "Pos"
                  Type = "Pos"
              if klass.__name__.startswith("Chain"):
                  Chain = "Chain"
              else:
                  Chain = ""
              ChainTyp = Chain + Typ
  
              self.Typ = Typ
              self.Type = Type
              self.Chain = Chain
              self.ChainTyp = ChainTyp
  
              self.LookupRecord = Type + "LookupRecord"
  
              if Format == 1:
                  self.Rule = ChainTyp + "Rule"
                  self.RuleSet = ChainTyp + "RuleSet"
              elif Format == 2:
                  self.Rule = ChainTyp + "ClassRule"
                  self.RuleSet = ChainTyp + "ClassSet"
  
      if self.Format not in [1, 2, 3]:
          return None  # Don't shoot the messenger; let it go
      if not hasattr(self.__class__, "_merge__ContextHelpers"):
          self.__class__._merge__ContextHelpers = {}
      if self.Format not in self.__class__._merge__ContextHelpers:
          helper = ContextHelper(self.__class__, self.Format)
          self.__class__._merge__ContextHelpers[self.Format] = helper
      return self.__class__._merge__ContextHelpers[self.Format]
  
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 9 for calling a global function with example usage: __merge_classify_context() and returns: self, None