// Defines two local variables (x, y).
    Variable<Complex> varX = new Variable.Local<Complex>("x");
    Variable<Complex> varY = new Variable.Local<Complex>("y");

    // f(x) = ix² + 2x + 1
    Polynomial<Complex> x = Polynomial.valueOf(Complex.ONE, varX);
    Polynomial<Complex> fx = x.pow(2).times(Complex.I).plus(
        x.times(Complex.valueOf(2, 0)).plus(Complex.ONE));
    System.out.println(fx);
    System.out.println(fx.pow(2));
    System.out.println(fx.differentiate(varX));
    System.out.println(fx.integrate(varY));
    System.out.println(fx.compose(fx));

    // Calculates expression.
    varX.set(Complex.valueOf(2, 3));
    System.out.println(fx.evaluate());

(let [v (Variable$Local. "x")]
  ...)