public bool IsM(List <int> directions)
{
return(directions.Count == 4 &&
onPlane.AreDirectionsOpposite(directions[0], directions[3]) &&
onPlane.AreDirectionsPerpendicular(directions[1], directions[2]) &&
onPlane.AreDirectionsNFarApart(directions[0], directions[2], 1) &&
onPlane.AreDirectionsNFarApart(directions[0], directions[1], 3) &&
onPlane.AreDirectionsNFarApart(directions[1], directions[3], 1));
}