*required virtual method* This class method, part of the sub-class
        API, converts a generator of ``(K, V)`` tuples (the *tuple protocol*)
        to one of the underlying collection type.

def tuples_to_coll(cls, generator, coerce=False):
        """*required virtual method* This class method, part of the sub-class
        API, converts a generator of ``(K, V)`` tuples (the *tuple protocol*)
        to one of the underlying collection type.
        """
        if cls != Collection:
            raise exc.CollectionDefinitionError(
                property='tuples_to_coll',
                coll='Collection',
            )