}
	case []ast.Spec:
		for _, s := range n {
			f.walk(s, context, visit)
		}
	}
}

// If x is of the form (T), unparen returns unparen(T), otherwise it returns x.
func unparen(x ast.Expr) ast.Expr {
	if p, isParen := x.(*ast.ParenExpr); isParen {
		x = unparen(p.X)
	}
	return x