anchor.diff:  open System
   open System.Collections.Concurrent
   open System.Collections.Generic
  +open System.Collections.Immutable
   open System.Diagnostics
   open System.IO
   open System.IO.MemoryMappedFiles
  
positive.code:             let rowinfo = rowReader i
              if keyComparer (keyFunc rowinfo) = 0 then 
                res := rowConverter rowinfo :: !res
          List.rev !res  
  
  
  let seekReadOptionalIndexedRow info =
  
negative.code:     (kind, parentIdx, valIdx)
  
  /// Read Table CustomAttribute.
  let seekReadCustomAttributeRow (ctxt: ILMetadataReader) mdv idx (attrRow: byref<CustomAttributeRow>) =
      let mutable addr = ctxt.rowAddr TableNames.CustomAttribute idx
      attrRow.parentIndex <- seekReadHasCustomAttributeIdx ctxt mdv &addr
      attrRow.typeIndex <- seekReadCustomAttributeTypeIdx ctxt mdv &addr
      attrRow.valueIndex <- seekReadBlobIdx ctxt mdv &addr
  
  /// Read Table FieldMarshal.
  let seekReadFieldMarshalRow (ctxt: ILMetadataReader) mdv idx = 
  