code: func (q *query) Exec(ctx context.Context) *Result {
  	if span := opentracing.SpanFromContext(ctx); span != nil {
  		span.SetTag(queryTag, q.stmt.String())
  	}
  
  	res, warnings, err := q.ng.exec(ctx, q)
  	return &Result{Err: err, Value: res, Warnings: warnings}
  }
docs: // Exec implements the Query interface.