def collect(self):
        """
        Walks self.migration_home and load all potential migration modules
        """
        for root, dirname, files in walk(self.migration_home):
            for file_name in file_filter(files, "*.py"):
                file_name = file_name.replace('.py', '')
                file = None
                try:
                    if file_name == '__init__':
                        continue
                    file, pathname, description = find_module(
                        file_name, [root])
                    load_module(file_name, file, pathname, description)
                finally:
                    if file is not None:
                        file.close()
Walks self.migration_home and load all potential migration modules