def __new__(mcs, name: str, bases: tuple, attrs: dict):
    """Create the class.

        Injects the 'reducers' attribute, a list of tuple matching token
        sequences to the name of the corresponding reduction methods.
        """
    reducers = []
    for key, value in attrs.items():
        if not hasattr(value, 'reducers'):
            continue
        for reduction in value.reducers:
            reducers.append((reduction, key))
    attrs['reducers'] = reducers
    return super().__new__(mcs, name, bases, attrs)
