Overrides superclass method and renames some properties

def get_configuration_dict(self, secret_attrs=False):
        """Overrides superclass method and renames some properties"""
        cd = super(TreeCollectionsShard, self).get_configuration_dict(secret_attrs=secret_attrs)
        # "rename" some keys in the dict provided
        cd['number of collections'] = cd.pop('number of documents')
        cd['collections'] = cd.pop('documents')
        return cd