code: function resolverOpts(resolveMode, maxLen, index, dtypes) {
    index = isUndefined(index) ? null : index;
    dtypes = isUndefined(dtypes) ? null : dtypes;
    return {
      resolveMode: resolveMode,
      maxLen: maxLen,
      index: index,
      dtypes: dtypes,
    };
  }
docs: Construct options for resolveSelector(). 'resolveMode' should be one of the values in RESOLVE_MODE. 'maxLen' should be the total length to index against. 'index' should be an AbstractIndex implementation if given. 'dtypes' should be a string vector of dtypes if given.