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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 validate_account_alias(iam_client, account_alias):
 """Exit if list_account_aliases doesn't include account_alias."""

    # Super overkill here using pagination when an account can only
    # have a single alias, but at least this implementation should be
    # future-proof
    current_account_aliases = []
    paginator = iam_client.get_paginator('list_account_aliases')
    response_iterator = paginator.paginate()
    for page in response_iterator:
        current_account_aliases.extend(page.get('AccountAliases', []))
    if account_alias in current_account_aliases:
        LOGGER.info('Verified current AWS account alias matches required '
                    'alias %s.',
                    account_alias)
    else:
        LOGGER.error('Current AWS account aliases "%s" do not match '
                     'required account alias %s in Runway config.',
                     ','.join(current_account_aliases),
                     account_alias)
        sys.exit(1)