\documentclass[a4paper]{article}
\usepackage[margin=18mm]{geometry}
\usepackage{corasdiagram}
\pagestyle{empty}
\newcommand{\examplefragment}[1]{%
  \IfFileExists{examples/fragments/#1}{%
    \input{examples/fragments/#1}%
  }{%
    \input{fragments/#1}%
  }%
}

\begin{document}

\section*{Treatment Overview Diagram}

\examplefragment{corasdiagram-treatment-overview-diagram-fragment.tex}

\end{document}
