code: function parseQueryString(query, options) {
    const result = {};
    let parsedQueryString = qs.parse(query);
  
    for (const key in parsedQueryString) {
      const value = parsedQueryString[key];
      if (value === '' || value == null) {
        throw new MongoParseError('Incomplete key value pair for option');
      }
  
      const normalizedKey = key.toLowerCase();
      const parsedValue = parseQueryStringItemValue(normalizedKey, value);
      applyConnectionStringOption(result, normalizedKey, parsedValue, options);
    }
  
    // special cases for known deprecated options
    if (result.wtimeout && result.wtimeoutms) {
      delete result.wtimeout;
      console.warn('Unsupported option `wtimeout` specified');
    }
  
    return Object.keys(result).length ? result : null;
  }
docs: Parses a query string according the connection string spec.
  
  @param {String} query The query string to parse
  @param {object} [options] The options used for options parsing
  @return {Object|Error} The parsed query string as an object, or an error if one was encountered