'Given action, domain and challege, return a change batch to use with
route53 call.
:param action: DELETE | UPSERT
:param domain: domain name
:param txt_challenge: challenge
:return: change set for a given action, domain and TXT challenge.'

@staticmethod
def get_dns_challenge_change_batch(action, domain, txt_challenge):

    return {'Changes': [{'Action': action, 'ResourceRecordSet': {'Name': '_acme-challenge.{0}'.format(domain), 'Type': 'TXT', 'TTL': 60, 'ResourceRecords': [{'Value': '"{0}"'.format(txt_challenge)}]}}]}
