`@attach` inside a Parser may now be stacked
`@attach` inside a Parser may now be stacked

For example:

    from purplex import Parser, attach

    class MyParser(Parser):
        @attach('slist : statement NEWLINE slist')
        @attach('slist : statement NEWLINE')
        @attach('slist : statement')
        def program(self, *args):
            pass

Stacking has the same effect as using '|' inside the production rule.

mtomwing/purplex