@staticmethod
def addable_cells(obj):
    """
        List object addable cells

        TESTS ::

            sage: from sage.combinat.partition import Partition
            sage: from sage_widget_adapters.combinat.partition_grid_view_adapter import PartitionGridViewAdapter
            sage: p = Partition([6, 5, 2, 1])
            sage: PartitionGridViewAdapter.addable_cells(p)
            [(0, 6), (1, 5), (2, 2), (3, 1), (4, 0)]
        """
    return obj.outside_corners()
