import typing


def merge_reports(reports: typing.Iterable[dict]) -> dict:
    """Merge the size reports in reports.

    :param reports: The reports to merge.
    :return: the merged report.
    """
    final_report = dict()
    for report in reports:
        for k, v in report.items():
            final_report[k] = final_report.get(k, 0) + v
    return final_report