@staticmethod
def merge(reports):
    """Works for dictionary reports. Merges the reports list of
        dictionaries in a single dictionary. The list of the first
        dictionary are extended by those of all subsequent lists."""
    report = reports[0]
    keys_report = list(report.keys())
    for other_report in reports[1:]:
        for key in keys_report:
            report[key] += other_report[key]
    return report
