How can I get hollow square bullets in Beamer?

\documentclass{beamer}\setbeamertemplate{items}[square]\setbeamertemplate{navigation symbols}{}\title{Minimum Working Example}\author{Minimally Working Author}\date{\today}\institute{Pan-Global Institute of Checklists}\begin{document}    \begin{frame}[fragile=singleslide]        \frametitle{Hollow Square Bullets?}            I would like some hollow, square bullets, please, as one might have on a checklist. Something like the \verb|\square| symbol, $\square$ \\            If this were a checklist, I would like to give that impression to the viewers:            \begin{itemize}                \item {Item one}                \item {Item two}                \item {Item three with sub-items}                    \begin{itemize}                        \item {Sub-item one with sub-items}                            \begin{itemize}                                \item {Sub-sub-item one}                                \item {Sub-sub-item two}                            \end{itemize}                        \item {Sub-item two}                    \end{itemize}                \item{Item four}            \end{itemize}    \end{frame}\end{document}