docs: function formatRequestErrors(request, errors) {
    const CONTEXT_BEFORE = 20;
    const CONTEXT_LENGTH = 60;
  
    const queryLines = request.getQueryString().split('\n');
    return errors.map(({locations = [], message}, ii) => {
      const prefix = (ii + 1) + '. ';
      const indent = ' '.repeat(prefix.length);
      return (
        prefix + message + '\n' +
        locations.map(({column, line}) => {
          const queryLine = queryLines[line - 1];
          const offset = Math.min(column - 1, CONTEXT_BEFORE);
          return [
            queryLine.substr(column - 1 - offset, CONTEXT_LENGTH),
            ' '.repeat(offset) + '^^^',
          ].map(messageLine => indent + messageLine).join('\n');
        }).join('\n')
      );
    }).join('\n');
  }