public void Ban(User bannedBy)
{
if (bannedBy.Role != UserRole.Moderator && bannedBy.Role != UserRole.Admin)
throw new ModeratorsRightsRequiredException();
if (Role == UserRole.Admin || Role == UserRole.Moderator)
throw new ModeratorsRightsRequiredException();
IsBanned = true;
BannedAt = DateTime.UtcNow;
}