public Number getWidth() {
        GroupingExpression w = getArg(1);
        return (w instanceof LongValue) ? ((LongValue)w).getValue() : ((DoubleValue)w).getValue();
    }
Returns the number of buckets to divide the result into.

@return The bucket count.
container-search/src/main/java/com/yahoo/search/grouping/request/FixedWidthFunction.java