BinOp makeBinOp(Token t, PythonTree left, List ops, List rights, List toks) {
BinOp current = new BinOp(t, castExpr(left), (operatorType)ops.get(0), castExpr(rights.get(0)));
for (int i = 1; i< rights.size(); i++) {
expr right = castExpr(rights.get(i));
operatorType op = (operatorType)ops.get(i);
current = new BinOp((Token)toks.get(i), current, op, right);
}
return current;
}