def _get_all_properties(vevent, prop):
    """Get all properties from a vevent, even if there are several entries

    example input:
    EXDATE:1234,4567
    EXDATE:7890

    returns: [1234, 4567, 7890]

    :type vevent: icalendar.cal.Event
    :type prop: str
    """
    if prop not in vevent:
        return list()
    if isinstance(vevent[prop], list):
        rdates = [leaf.dt for tree in vevent[prop] for leaf in tree.dts]
    else:
        rdates = [vddd.dt for vddd in vevent[prop].dts]
    return rdates