3.3. Sather source files

abstract class $PLANET is ... end;
class GAS_GIANT < $PLANET is ... end;

source_file ==>
        [ abstract_class_definition | class ] { ; [ abstract_class_definition | class ] }

Sather source files consist of semicolon separated lists of classes. Execution of a Sather program begins with a routine named 'main' in a specified class (See Special feature names), usually 'MAIN'.