code: function normalizeClauses (conf) {
    const output = {};
    const validPath = Object.keys(conf).filter(path => Array.isArray(conf[path]));
    validPath.forEach(path => {
      const validClauses = conf[path].filter(c => c.value !== '');
      if (validClauses.length) {
        output[path] = validClauses;
      }
    });
    return output;
  }
docs: avoid useless filter lookup (improve perf)