code: func (n *NamedStmt) QueryContext(ctx context.Context, arg interface{}) (*sql.Rows, error) {
  	args, err := bindAnyArgs(n.Params, arg, n.Stmt.Mapper)
  	if err != nil {
  		return nil, err
  	}
  	return n.Stmt.QueryContext(ctx, args...)
  }
docs: // QueryContext executes a named statement using the struct argument, returning rows.
  // Any named placeholder parameters are replaced with fields from arg.