def calculate_report_grade(*results):
    """Calculate a total grade by summing the analyzed results

    The grade value would be one of [A+, A, B, C, D, E, F]

    Args:
        results: A list of Grade-based results to calculate a grade

    Returns:
        Grade value as string
    """
    total_score = 0

    for result in results:
        total_score += result.get_weighted_score()

    if total_score > 90:
        return 'A+'
    elif total_score > 80:
        return 'A'
    elif total_score > 70:
        return 'B'
    elif total_score > 60:
        return 'C'
    elif total_score > 50:
        return 'D'
    elif total_score > 40:
        return 'E'
    else:
        return 'F'