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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 get_lambda_alias_arn(app, account, region):
 """Get lambda alias ARN. Assumes that account name is equal to alias name. Args: account (str):
 AWS account name. region (str):
 Region name, e.g. us-east-1 app (str):
 Lambda function name Returns: str: ARN for requested lambda alias """

    session = boto3.Session(profile_name=account, region_name=region)
    lambda_client = session.client('lambda')

    lambda_aliases = lambda_client.list_aliases(FunctionName=app)

    matched_alias = None
    for alias in lambda_aliases['Aliases']:
        if alias['Name'] == account:
            lambda_alias_arn = alias['AliasArn']
            LOG.info('Found ARN for alias %s for function %s', account, app)
            matched_alias = lambda_alias_arn
            break
    else:
        fatal_message = 'Lambda alias {0} of function {1} not found'.format(account, app)
        LOG.fatal(fatal_message)
        raise LambdaAliasDoesNotExist(fatal_message)
    return matched_alias