static imagPartOf(v) {
        if (v instanceof Complex) {
            return v.imag;
        }
        if (typeof v === "number") {
            return 0;
        }
        throw new DetailedError("Unrecognized value type.", {v});
    }
Returns the imaginary component of a Complex value, or else 0 for integer and float values.
@param {!number|!Complex} v
@returns {!number}