Class Required

docopt.py:226–236

class Required(ParentPattern):

    def match(self, left, collected=None):
        collected = [] if collected is None else collected
        l = left
        c = collected
        for p in self.children:
            matched, l, c = p.match(l, c)
            if not matched:
                return False, left, collected
        return True, l, c


class Optional(ParentPattern):