In Python’s full grammar specification this part can be found:
decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE decorators: decorator+ decorated: decorators (classdef | funcdef | async_funcdef)
This is basically saying,
decorators start with an @,
can optionally have parameters,
must be in a line by itself,
and we can stack one or several decorators before a class or function definition.