class BinData::LazyEvaluator

def index
  return @overrides[:index] if defined?(@overrides) && @overrides.key?(:index)
  child = @obj
  parent = @obj.parent
  while parent
    if parent.respond_to?(:find_index_of)
      return parent.find_index_of(child)
    end
    child = parent
    parent = parent.parent
  end
  raise NoMethodError, "no index found"
end