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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 _calc_validation_statistics(validation_results):
 """ Calculate summary statistics for the validation results and return ``ExpectationStatistics``. """

    # calc stats
    successful_expectations = sum(exp["success"] for exp in validation_results)
    evaluated_expectations = len(validation_results)
    unsuccessful_expectations = evaluated_expectations - successful_expectations
    success = successful_expectations == evaluated_expectations
    try:
        success_percent = successful_expectations / evaluated_expectations * 100
    except ZeroDivisionError:
        success_percent = float("nan")

    return ValidationStatistics(
        successful_expectations=successful_expectations,
        evaluated_expectations=evaluated_expectations,
        unsuccessful_expectations=unsuccessful_expectations,
        success=success,
        success_percent=success_percent,
    )