class RSpec::Core::MemoizedHelpers::ContextHookMemoizedHash

def self.fetch(key, &block)
  description = if key == :subject
    "subject"
  else
    "let declaration `#{key}`"
  end
  raise <<-EOS
ption} accessed in #{article} #{hook_expression} hook at:
erFilter.first_non_rspec_line}
d `subject` declarations are not intended to be called
icle} #{hook_expression} hook, as they exist to define state that
 between each example, while #{hook_expression} exists to
ntention}.
end

def self.isolate_for_context_hook(example_group_instance)
  hash = self
  example_group_instance.instance_exec do
    @__memoized = hash
    begin
      yield
    ensure
      @__memoized = nil
    end
  end
end