code: function singleColNameLookup(selector, colNames) {
    if (isUndefined(selector)) {
      throw new Error('selector must not be undefined');
    }
    selector = ensureScalar(selector);
    if (isNumber(selector)) {
      return resolveIntIdx(selector, colNames.values.length);
    } else if (isString(selector) || selector === null) {
      var intInds = colNames._getIndex().lookupKey([selector]);
      if (intInds === null) {
        throw new Error('invalid column name: ' + selector);
      } else if (typeof intInds !== 'number') {
        // must be an array, so use the first element
        intInds = intInds[0];
      }
      return intInds;
    } else {
      throw new Error('column selector must be an integer or string');
    }
  }
docs: Returns the integer index of the first occurrence of a single column name or throws an error if 'selector' is invalid or no occurrence is found. 'selector' can be a single integer or string expressed as a scalar, array, or vector.  'colNames' must be a string vector