function pushDim(dimIdxArr, idxFrom, idxCount) {
        for (var i = 0; i < idxCount; i++) {
            dimIdxArr.push(idxFrom + i);
        }
    }
The rule should not be complex, otherwise user might not
be able to known where the data is wrong.
The code is ugly, but how to make it neat?

@param {module:echars/data/Source} source
@param {number} dimIndex
@return {BE_ORDINAL} guess result.