```
if (FALSE) {
cppFunction(
'int fibonacci(const int x) {
if (x == 0) return(0);
if (x == 1) return(1);
return (fibonacci(x - 1)) + fibonacci(x - 2);
}')
cppFunction(depends = "RcppArmadillo",
'List fastLm(NumericVector yr, NumericMatrix Xr) {
int n = Xr.nrow(), k = Xr.ncol();
arma::mat X(Xr.begin(), n, k, false);
arma::colvec y(yr.begin(), yr.size(), false);
arma::colvec coef = arma::solve(X, y);
arma::colvec resid = y - X*coef;
double sig2 = arma::as_scalar(arma::trans(resid)*resid/(n-k) );
arma::colvec stderrest = arma::sqrt(
sig2 * arma::diagvec(arma::inv(arma::trans(X)*X)));
return List::create(Named("coefficients") = coef,
Named("stderr") = stderrest
);
}')
cppFunction(plugins=c("cpp11"), '
int useCpp11() {
auto x = 10;
return x;
}')
}
```

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