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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 getGerritChanges(props):
 """ Get the gerrit changes This method could be overridden if really needed to accommodate for other custom steps method for fetching gerrit changes. :param props: an IProperty :return: (optionally via deferred) a list of dictionary with at list change_id, and revision_id, which format is the one accepted by the gerrit REST API as of /changes/:change_id/revision/:revision_id paths (see gerrit doc) """

        if 'gerrit_changes' in props:
            return props.getProperty('gerrit_changes')

        if 'event.change.number' in props:
            return [{
                'change_id': props.getProperty('event.change.number'),
                'revision_id': props.getProperty('event.patchSet.number')
            }]
        return []