each_causeみたいなのがほしい

each_cause_sample.rb

class StandardError
  def each_cause(&block)
    e = self
    while e
      yield e
      e = e.cause
    end
  end
end

begin
  raise StandardError, '1st'
rescue => e1
  begin
    raise StandardError, '2nd'
  rescue => e2
    e2.each_cause do |ex| # <--- こんな感じ
      puts ex.message
    end
  end
end

# % ruby each_cause_sample.rb
# 2nd
# 1st