!GeometricShape >>
 ...
;

Point : GeometricShape >>                        Line : GeometricShape >>
 GeometricShape : _                               GeometricShape : _
 ...                                              ...
;                                                ;

Rectangle : GeometricShape >>                    Area : GeometricShape >>
 GeometricShape : _                               GeometricShape : _
 ...                                              ...
;                                                ;


