steamIdToEther[old_steamid][i]=steamIdToEther[old_steamid][steamIdToEther[old_steamid].length-1];//move last element into the position of our item we want to remove
steamIdToEther[old_steamid].pop();//delete last item which is now a duplicate
}
}
}
//update eth->steamid list
etherToSteamID[sender]=_steamId64;
//if steamid->eth list does not already contain our sender then add