private static double linearInterpolationOf(double x0, double x1, double f0, double f1, double x) {
        return f0 + (f1 - f0) / (x1 - x0) * (x - x0);
    }
Maps a given raw estimate to a bias correction value. The callee should subtract the bias from the raw estimate
to get a bias corrected HLL estimate. Uses linear interpolation when no exact value exist.

@param rawEstimate The raw HLL estimate
@return The estimated bias for the given raw estimate.
searchlib/src/main/java/com/yahoo/searchlib/aggregation/hll/BiasEstimator.java