code: def __find_child_classes(self, file):
          
  
          child_classes = []
          folder, name = os.path.split(file)
          name = os.path.splitext(name)[0]
  
          import imp
          module = imp.load_source(name, file)
  
          def filter_classes(m):
              if inspect.isclass(m):
                  if inspect.getmro(m)[1] == self.__base_class:
                      return True
              return False
  
          for name, obj in inspect.getmembers(module, filter_classes):
              child_classes.append(obj)
  
          return child_classes
docs: Return a list of all <__base_class> based classes found in <file>