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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def koji_instance(config, message, instance=None, *args, **kw):
 """ Particular koji instances You may not have even known it, but we have multiple instances of the koji build system. There is the **primary** buildsystem at `koji.fedoraproject.org <http://koji.fedoraproject.org>`_ and also secondary instances for `ppc <http://ppc.koji.fedoraproject.org>`_, `arm <http://arm.koji.fedoraproject.org>`_, and `s390 <http://s390.koji.fedoraproject.org>`_. With this rule, you can limit messages to only those from particular koji instances (like the **primary** one if you want to ignore the secondary ones). You should use this rule **in combination** with other koji rules so you get only a *certain subset* of messages from one instance. You almost certainly do not want **all** messages from a given instance. You can specify several instances by separating them with a comma ',', i.e.: ``primary,ppc``. """


    instance = kw.get('instance', instance)
    if not instance:
        return False

    instances = [item.strip() for item in instance.split(',')]
    return message['msg'].get('instance') in instances