Overleaf/services/clsi/test/acceptance/fixtures/examples/knitr/main.Rtex

\documentclass{article}
\begin{document}

Hello world $x^2 = 0$.

%% chunk options: cache this chunk
%% begin.rcode my-cache, cache=TRUE
% set.seed(123)
% x = runif(10)
% sd(x)  # standard deviation
%% end.rcode

\end{document}