code: def cost(self):
      if self._cost is None:
          self._cost = (
              # 2 bytes to store the offset to this subtable in the Lookup table above
              2
              # Contents of the subtable
              # From: https://docs.microsoft.com/en-us/typography/opentype/spec/gpos#pair-adjustment-positioning-format-2-class-pair-adjustment
              # uint16	posFormat	Format identifier: format = 2
              + 2
              # Offset16	coverageOffset	Offset to Coverage table, from beginning of PairPos subtable.
              + 2
              + self.coverage_bytes
              # uint16	valueFormat1	ValueRecord definition — for the first glyph of the pair (may be zero).
              + 2
              # uint16	valueFormat2	ValueRecord definition — for the second glyph of the pair (may be zero).
              + 2
              # Offset16	classDef1Offset	Offset to ClassDef table, from beginning of PairPos subtable — for the first glyph of the pair.
              + 2
              + self.classDef1_bytes
              # Offset16	classDef2Offset	Offset to ClassDef table, from beginning of PairPos subtable — for the second glyph of the pair.
              + 2
              + self.classDef2_bytes
              # uint16	class1Count	Number of classes in classDef1 table — includes Class 0.
              + 2
              # uint16	class2Count	Number of classes in classDef2 table — includes Class 0.
              + 2
              # Class1Record	class1Records[class1Count]	Array of Class1 records, ordered by classes in classDef1.
              + (
                  self.ctx.valueFormat1_bytes
                  + self.ctx.valueFormat2_bytes
              )
              * len(self.indices)
              * self.width
          )
      return self._cost
  
imports: import logging
  import os
  from collections import defaultdict, namedtuple
  from functools import reduce
  from itertools import chain
  from math import log2
  from typing import DefaultDict, Dict, Iterable, List, Sequence, Tuple
  from fontTools.config import OPTIONS
  from fontTools.misc.intTools import bit_count, bit_indices
  from fontTools.ttLib import TTFont
  from fontTools.ttLib.tables import otBase, otTables
label_desc: Use image node_id 5 for calling the Cluster obj's underlying member method code with example usage: obj.cost() and returns: self