code: function hasInterpolatingAmpersand(selector) {
    for (let i = 0, l = selector.length; i < l; i++) {
      if (selector[i] !== "&") {
        continue;
      }
  
      if (!_.isUndefined(selector[i - 1]) && !isCombinator(selector[i - 1])) {
        return true;
      }
  
      if (!_.isUndefined(selector[i + 1]) && !isCombinator(selector[i + 1])) {
        return true;
      }
    }
  
    return false;
  }
docs: An "interpolating ampersand" means an "&" used to interpolate within another simple selector, rather than an "&" that stands on its own as a simple selector