\documentclass{article}
\usepackage[margin=20mm]{geometry}
\usepackage[libraries=none]{gradbars}
\gradbarsdeclarelibrary{starter}{table}{gradbars-contrib-starter.sty}
\usegradbarslibrary{starter,starter}
\gradbarsifbackendcapable{starter-tikz}{bar}{}
 {\PackageError{starter-example}{Missing backend capability}{Check library loading.}}
\setlength{\parindent}{0pt}
\begin{document}
\section*{Third-party extension starter}
\gradgraphic[max=100,precision=2]{starter-score}{72.125}\par\medskip
\gradbar[backend=starter-tikz,formatter=starter-number,precision=2]{72.125}\par
\begin{center}
\begin{gradtable}[align=c,header align=c,style=starter-report,width=\linewidth]
\gradcolumn{name}{Method}
\gradcolumn[type=number,formatter=starter-number,aggregate=mean]{score}{Score}
\gradrow{Alpha,72.125}\gradrow{Beta,90}\gradsummary{Mean}
\end{gradtable}
\end{center}
\gradbarsiflibraryloaded{starter}{\typeout{STARTER-CHECK:OK}}
 {\PackageError{starter-example}{Library did not load}{Check registration.}}
\end{document}