# For the life of me I can't find the runaway argument here — but then I'm very new to all this

\documentclass[11pt, oneside]{article}
\usepackage{geometry}
\geometry{a4paper}
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage{arydshln}
\usepackage[table]{xcolor}
\usepackage{pifont}

\begin{document}

\begin{center} \renewcommand*\arraystretch{1.2}


\end{document}