\NeedsTeXFormat{LaTeX2e} % specify required latex format
\ProvidesClass{masterthesis}[2019/01/03 Masterthesis Class]

% Fallback, pass all unknown options to base class
\DeclareOption*{
    \PassOptionsToClass{\CurrentOption}{scrreprt}
}

% Process given options
\ProcessOptions\relax

% Load base class
\LoadClass[a4paper]{scrreprt}

% do some stuff

% mandatory last line
\endinput
