public static NErrorCode EntityVarsAndConstants(ObjRef exprPtr, ref NativeArray res)
 => ExceptionEncode(ref res, exprPtr,
                    exprPtr => NativeArray.Alloc(exprPtr.AsEntity.VarsAndConsts.Select(v => (Entity)v))
                    );
 public static NErrorCode EntityNodes(ObjRef exprPtr, ref NativeArray res)
 => ExceptionEncode(ref res, exprPtr,
                    exprPtr => NativeArray.Alloc(exprPtr.AsEntity.Nodes)
                    );