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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def destroy_cloudwatch_event(app='', env='dev', region=''):
 """Destroy Cloudwatch event subscription. Args: app (str):
 Spinnaker Application name. env (str):
 Deployment environment. region (str):
 AWS region. Returns: bool: True upon successful completion. """


    session = boto3.Session(profile_name=env, region_name=region)
    cloudwatch_client = session.client('events')

    event_rules = get_cloudwatch_event_rule(app_name=app, account=env, region=region)

    for rule in event_rules:
        cloudwatch_client.remove_targets(Rule=rule, Ids=[app])

    return True