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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Wed, 21 Jan 2015 10:27:21 -0700
Subject: Re: Trees
To: Python <python-list@python.org>
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Xref: csiph.com comp.lang.python:84131

On Wed, Jan 21, 2015 at 9:15 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> class MultiSet(MutableSet):

In retrospect this probably shouldn't derive from MutableSet, since
that carries the expectation that all elements are unique (much like
how bool shouldn't be subclassed). For instance, collections.Set
includes some operators that aren't compatible with the second operand
being a multiset.